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Bureau of Mines Information Circular/1982 




Mine Illumination 

Proceedings: Second International Mine Lighting 
Conference of the International Commission 
on Illumination (CIE) 



Compiled by K. L. Whitehead and W. H. Lewis 




UNITED STATES DEPARTMENT OF THE INTERIOR 



V 



I 



*<\ 



I 



I 



I 






5 ^ "^ 



Information Circular 8886 



Mine Illumination 

Proceedings: Second International Mine Lighting 
Conference of the International Commission 
on Illumination (CIE) 



Compiled by K. L. Whitehead and W. H. Lewis 




UNITED STATES DEPARTMENT OF THE INTERIOR 
James G. Watt, Secretary 

BUREAU OF MINES 
Robert C. Horton, Director 



- 1 ^ 



This publication has been cataloged as follows: 



International Mine Lighting Conference of the International Com- 
mission on Illumination (CIE) (2nd : 198L : Beckley, W. Va.). 
Mine illumination. 

(Information circular ; 8886) 

Includes bibliographical references. 

Supt. of Docs, no.: I 28.27:8886. 

1. Mine lighting— Congresses. I. Whitehead, K. L. (Kenneth L.). 
II. Lewis, W. H. (William H.). III. International Commission on Il» 
lumination. IV. Title. V. Series: Information circular( United States. 
Bureau of Mines) ; 8886. 

TN295.U4- [TN301] 622s [622'.47] 82-600187 AACR2 



CONTENTS 

Page 

Second International Mine Lighting Conference of the International 
Commission on Illumination (CIE), by K. L. Whitehead 
and W. H. Lewis 1 

Mine lighting and the CIE, By Dr. Sylvester K. Guth 11 

Discomfort glare sensitivity of underground mine personnel, by 

Dr. Sylvester K. Guth 17 

Mine underground illumination in Poland, by Adam Peretiatkowicz, Dr . Sc . . 22 

Problems of electric mine lighting in the work of CIE, by 

Adam Pere t i atkowic z , Dr . Sc 32 

Modern underground lighting techniques. New material which the 
lighting fittings consist of; suitable constructions and 
practical testing, by Ing . Georg Pawlowski 44 

UMWA/BCOA/MSHA mine illumination survey, by Mr. Glenn Beckett 62 

Overview of U.S. Bureau of Mines illumination research program, 

by Mr. William H. Lewis 74 

Underground lighting acceptance procedures, by 

Mr. Freddy M. Huffman, P.E 96 

Illumination in South African gold mines, by Mr. R. Hemp Ill 

Mine lighting research and development work in Bulgaria, 

by Eng . Gancho Ganchev 1 28 

Luminous measurements in firedamp zones of coal mines, 

by Dr. -Ing. Bruno Weis 144 

Reflectance measurements in mining, by Mr. Donald Trotter 154 

Visual attention locations and a methodology for assessing 
visibility from underground mining equipment, by 
Mark S. Sanders , Ph .D 172 

Disability glare studies on underground mine personnel, 

by Mr. C. L. Crouch 184 



11 



CONTENTS— Continued 

Page 

Determination of safety lighting needs for exterior and 
interior areas of coal preparation plants, 
by Richard L . Vincent 192 

Cost effective illumination of underground machinery, 

by Mr. John R. Parker, P.E 213 

Coal industry experience with mine illumination systems: 
maintenance requirements and personnel acceptance, by 
Mr . Jon Yingl ing 237 

Efforts to design lighting systems into underground mining 

equipment , by Mr . Owen J . Wright 261 

Illuminating large surface machines, problems and solutions, 

by Mr. David Hottinger 270 

Lighting for large, mobile, surface mining equipment, by 

Mart in H . Wahl 305 

Definition of illumination requirements for underground metal 

and nonmetal mines, by William H. Crooks, Ph.D 318 

Appendix A 334 

Append ix B 337 



MINE ILLUMINATION 

Proceedings: Second International Mine Lighting Conference of the International 

Commission on Illumination (CIE) 

Compiled by K. L. Whitehead 1 and W. H. Lewis2 



ABSTRACT 

The U.S. Bureau of Mines, Department of Labor, and United States National 
Committee of the CIE hosted the TC4.10 Mine Lighting Committee Meeting and 
Second International CIE Mine Lighting conference at the MSHA Academy in 
Beckley, WV from October 12-16, 1981. This was the first time the meeting and 
conference had been held in the United States. 

The TC4.10 Mine Lighting Committee, chaired by Dr. Adam Peretiatkowicz of 
Poland, was attended by 15 committee members and six guests representing eight 
countries. Discussion during the meeting covered mine lighting instrumen- 
tation, open cast (surface mine) lighting, and lighting sources. The com- 
mittee also reviewed a draft of proposed lighting terminology and suggested 
changes to make the definitions more acceptable to representatives of the 
nations present. 

The mine-lighting conference featured 20 papers presented by 18 speakers 
representing six countries. The papers covered all phases of mine lighting, 
including research, hardware development and application, personnel accept- 
ance, and requirements for system maintenance. The conference attracted 126 
attendees and also included displays by eight lighting hardware manufacturers 
and four mining machine manufacturers. Papers from the conference are being 
published by the Government Printing Office, with copies presented to the 
conference attendees. Copies will be available to others interested through 
the NTIS. During the course of the TC4.10 meetings and conference, committee 
members toured three mining equipment assembly plants, and six of the foreign 
representatives visited a longwall installation in an underground mine. 

Planning and administrative services for the meeting and conference were 
handled by Bituminous Coal Research, Inc., under USBM Contract H0318038. 



Supervising Engineer, Bituminous Coal Research, Inc., Monroeville, PA 

^•Group Supervisor, Mine Illumination Reseai 
Pittsburgh Research Center, Pittsburgh, PA 



''-Group Supervisor, Mine Illumination Research, U.S. Bureau of Mines, 



TC4.10 MINE LIGHTING COMMITTEE MEETING 

The TC4.10 Mine Lighting Committee was formed in 1975 at Session XVIII 
of the CIE in London, England. The committee's main tasks are to prepare 
international recommendations for underground mine lighting, coordinate ideas 
on the basic parameters of mine lighting, and make recommendations for light- 
ing particular areas such as the coal face. 

To help achieve these goals, three subcommittees have been formed as 
follows : 

SC4.10A - Mine Lighting Measurements 

Chairman - Dr.-Ing. Bruno Weis 

SC4.10B - Open Cast Lighting 

Chairman - Kenneth Whitehead 

SC4.10C - Mine Light Sources 

Chairman - Don Trotter 

Members of the TC4.10 International Committee and of the American Mine 
Lighting Committee are included as Appendix A. 

The agenda for the committee meeting follows. Minutes of the meeting are 
being prepared by Dr. Peretiatkowicz, Committee Chairman, for distribution to 
committee members. Copies can be obtained by contacting the chairman or a 
committee member. The CIE documents reviewed at the meeting were: 

1. Minutes of the TC4.10 Meeting at Kokotek, April 21-22, 1980 

2. Mine Lighting Terminology Report - 5th Draft 

3. International Recommendation for Underground Mine Lighting - 5th 
Draft 



TC4.10 COMMITTEE MEETING AGENDA 

I. TECHNICAL COMMITTEE TC4.10 Held October 12-13, 1981 

Dr. Adam Peretiatkowicz, Chairman 

1. Opening of the meeting and welcome by the Chairman 

2. Appointment of the Secretary and Reporters 

3. Acceptance of the meeting program 

4. The Chairman's brief report on the TC4.10 activities since Kyoto 
Session. Minutes of the meeting in Kokotek and report on the 
Symposium "100 years of Electrical Illumination in Silesian 
Collieries 11 

5. Discussion on the TC4.10 activity and approval of the Chairman's 
proposition 

I I. Subcommittee SC4.10A, "Mine Lighting Measurements" 

Dr.-Ing. Bruno We is, Chairman 

1. Presentation of the working program 

2. Dr. Weis, Germany, propositions 

3. Discussion and approval of the working program in the years 
1981 to 1983 

III. Subcommittee SC4.10B, "Open Cast Lighting" 

1. Draft of the working program 

2. Discussion 

3. Appointment of the Subcommittee Chairman* 

4. Approval of the working program 

IV. Subcommittee SC4.10C, "Mine Light Sources" 

Prof. Donald Trotter, Chairman 

1. Presentation of the SC4.10C activity since April 1980 

2. Discussion 

3. Discussion and approval of the Chairman's working program for 
the coming years 

V. Technical Committee TC4.10 

Dr. Adam Peretiatkowicz, Chairman 

1. Presentation of the 5th draft of the CIE Recommendation for 
Underground Mine Lighting 

2. Discussion 

3. Presentation and approval of the 5th draft of the TC4.10 
terminology and discussion on further works 

4. Information of the CIE reorganization 

5. Approval of the Subcommittees' working programs presented 
by the SC Chairmen 

6. Future Committee meetings in 1982 and 1983 

7. Other business 

8. Closing the meeting 



*Mr . Kenneth L. Whitehead, Bituminous Coal Research, Inc., was appointed 
Chairman of the SC4.10B Committee. 



SECOND INTERNATIONAL MINE LIGHTING CONFERENCE 

The Second International Mine Lighting Conference, held in conjunction 
with the TC4.10 Mine Lighting Committee Meeting, was a part of the CIE program 
of international cooperation and exchange of information among member coun- 
tries on all matters relating to the art and science of lighting. Membership 
consists of 30 countries, each having a National Committee of individual 
members who devote their time and talent to the objectives of the organiza- 
tion. In addition, individuals from 10 other countries have Associate Member 
status. Members of the United States National CIE Committee are listed in 
Appendix B. 

The objectives of the CIE are: 

1. to provide an international forum for all matters relating to the 
art and science of lighting; 

2. to promote by all appropriate means the study of such matters; 

3. to provide for the interchange of lighting information among the 
different countries; 

4. to prepare and publish international agreements in the field of 
lighting. 

The work of the CIE is carried on by 26 Technical Committees, each of 
which is assigned to a member country. These cover subjects ranging from 
those which involve basic and fundamental matters to all types of lighting 
applications. The reports and guides developed by these international com- 
mittees are possible only through an organization such as the CIE and are 
accepted throughout the world. 

A Plenary Session is held every four years at which the work of the 
committees is reviewed and reported, and plans are made for the future. The 
CIE is recognized as representing the authority on all aspects of light and 
lighting. As such it occupies an important position among international 
organizations . 

All but one of the papers included in this report were presented at the 
Second International CIE Mine Lighting Conference. That paper, "Definition of 
Illumination Requirements for Underground Metal and Nonmetal Mines," was 
submitted only for publication in the proceedings. The purpose of the con- 
ference was to provide a program of both technical interest and practical 
value to attendees associated with underground, strip, and metal-nonmetal 
mining. 

Speakers invited to present papers were selected from individuals in- 
volved in management and research activities related to mine lighting, as well 
as those who have effectively applied lighting technology to the mining 



industry. The conference planning committee felt that the publication of the 
experience of these individuals would make a significant contribution to the 
data base concerning the effect of mine lighting on improved safety, environ- 
mental control, and production. 

In addition to the speakers, manufacturers of mine-lighting hardware and 
of mining equipment displayed their products to provide attendees with infor- 
mation on currently available hardware. The manufacturers which participated 
in the conference are listed in Table 1 and illustrations of the display areas 
are shown in Figures 1 through 4. 

CONFERENCE PAPERS 

Included in this section are the keynote address delivered by Dr. S. K. 
Guth , Past President of CIE ; conference papers; and biographical sketches of 
the speakers presenting them. The speakers represent expertise in all phases 
of mine lighting and reflect international experience in the development and 
application of mine lighting technology. 



TABLE 1 . - Manufacturers participating in the Second 
International Mine Lighting Conference 



Lighting Equipment Manufacturers 

Mcjunkin Corporation 

PO Box 513 

Charleston, West Virginia 25322 

Mine Safety Appliances 
600 Penn Center Boulevard 
Pittsburgh, PA 15235 

National Mine Service 
U.S. Route 22 & 30 West 
Old Steubenville pike 
Oakdale, PA 15071 

Ocenco , Inc . 

PO Box 8 

101 Industrial Park 

Blairsville, PA 15717 



Mining Equipment Manufacturers 

Fairchild Inc. 

PO Box 890 

Beckley, West Virginia 25801 

FMC Corporation 

Mining Equipment Division 

Tenth and Belt line 

Fairmont , West Virginia 26554 

Lee-Norse Company 

401 Rag land Road 

Beckley, West Virginia 25801 

Long-Airdox 

PO Box 331 

Oak Hill, West Virginia 25901 



Mining Controls, Inc. 

PO Box 1141 

Beckley, West Virginia 25801 

Permalux Lighting Products, Inc. 

Box 351 

Maple Shade, New Jersey 08052 

Safety Lamp of Houston, Inc. 
15550 West Hardy Road 
Houston, Texas 77060 



Siemens Corporation 
186 Wood Avenue South 
Iselin, New Jersey 08830 




FIGURE 1. - Mining equipment display area, 




FIGURE 2. - Lighting hardware manufacturers' display area, 




FIGURE 3. - Lighting hardware manufacturers' display area. 



10 




FIGURE 4. - Lighting hardware manufacturers' display area. 



11 



KEYNOTE ADDRESS: Mine Lighting and the CIE 



TITLE OF PAPER: 



Discomfort Glare Sensitivity 
of Underground Mine Personnel 



AUTHOR: Dr. Sylvester K. Guth (Retired) 

Lamp Division of General Electric 



Dr. Guth received a B.S. Degree and a Professional Degree in Electrical 
Engineering from the University of Wisconsin, and Doctor of Ocular Science 
Degree by the Northern Illinois College of Optometry. 

He has been active in the work of the Illuminating Engineering Society 
(IES) as chairman of the Society's Committee on Recommendations for Quantity 
and Quality of Illumination, and its Nomenclature Committee. He also has 
served on the Papers, Illumination Performance Recommendation, Color and 
Illumination, and Research Committees, and for many years was the Society's 
official representative to the American Association for the Advancement of 
Science. He has served for many years on the Technical Advisory Committee 
for Light and Vision of the Illuminating Research Institute. Dr. Guth was 
made a Fellow of the IES in recognition of his outstanding technical 
contributions . 

In 1967, Dr. Guth was awarded the IES Gold Medal, the Illuminating 
Engineering Society's highest honor "in recognition of a lifetime devoted to 
research on light and vision, and especially for his pioneer work in the 
psychological evaluation of glare sensation, with its relation to visual 
comfort." 



Dr. Guth was elected a Fellow of the American Academy of Optometry and 
of the American Association for the Advancement of Science, and is a member 
of the Optical Society of America, the Inter-Society Color Council, the 
Illuminating Engineering Society (London) , the National Research Council 
Committee on Vision, and the American Society for Photobiology . 

Dr. Guth joined the Lamp Division of G.E., Nela Park, in 1930, and was 
put in charge of lighting research activities in 1950. 

From 1956 to 1968, he was manager of the Radiant Energy Effects Labora- 
tory, responsible for researches on the effects of radiant energy on man, 
animals, and plants. On January 1, 1969, he was appointed Manager, Applied 
Research, and was responsible for researches in vision, visibility, visual 
and human performance, visual comfort, color and physiological effects of 
radiant energy (UV, visible, and IR) . 



12 



During his career with General Electric, Dr. Guth performed or directed 
most of the investigations at Nela Park in the fields of light, vision, and 
seeing. He developed many criteria and techniques used in evaluating visi- 
bility, contrast sensitivity, ease of seeing, glare and quality of lighting. 
He also devised demonstration materials and equipment to illustrate the ef- 
fectiveness of illumination on these factors. His work on discomfort glare 
has been recognized all over the world, and is the basis of the Visual Comfort 
Probability (VCP) method adopted in the Illuminating Engineering Society of 
North America. 

He retired in 1974. 



13 



MINE LIGHTING AND THE CIE 

by 

Sylvester K. Guth 1 



ABSTRACT 

Mining has been and continues to be an important industry in many 
countries. It was recognized as an area involving unique snd special lighting 
problems in 1931 when the CIE established Study Committee 29. Since then, 
except for one brief period, mine lighting has been among its more active 
committees. Currently, 19 countries are contributing to the work of CIE 
Committee TC-4.10. The present Conference — the second of its type — is an 
excellent example of the importance attached to mine lighting. It is expected 
that the papers and the discussions will provide considerable useful infor- 
mation for the Committee. 

TEXT 

As a long-time active participant in the technical and administrative 
affairs of the International Commission on Illumination, I was delighted to be 
invited to be the keynote speaker at this Second International Conference on 
Mine Lighting. I am particularly pleased with the decision to hold the 
Conference in the United States. In looking back over the years, I believe 
this is only one of two or three international meetings cosponsored by a CIE 
Committee that has been held in this country. For a long time the CIE Board 
of Administration and the Action Committee have been encouraging the Technical 
Committees to sponsor meetings and synposia and to seriously consider holding 
them outside of Europe. Doing so emphasizes the world-wide internat ionality 
of the CIE and also permits the participation of many people who otherwise 
would not be able to contribute to its work. Thus, speaking for the CIE 
Administration, I welcome you to this Conference. 

On behalf of its President, Mr. Franc Grum, I also bring you greetings 
from the United States National Committee of the CIE. One of our hopes is 
that the success of this Conference will demonstrate the effectiveness of 
holding such meetings over here and to stimulate others to do the same. 

My task, as the keynote speaker, is to set the stage for this Conference. 
To do this, it seems appropriate to review very briefly the mine lighting 
activity in the CIE, with special emphasis on the past several quadrennia. 



Ipast President, International Commission on Illumination, South Euclid, Ohio 



14 

Mining is an important industry in many countries and has been for count- 
less years. It was recognized as an area involving unique and special light- 
ing problems in 1931 when the CIE established Study Committee 29. For the 
next 34 years mine lighting was among the more active of the Secretariat 
Committees. At each Plenary Session during this period, the reports on mine 
lighting problems and developments in various countries and the individual 
papers resulted in considerable discussion. The subjects dealt with included 
visibility, glare, measurement of illumination and luminance, lighting methods 
and regulations. While no definitive technical reports were issued by the 
Committee, the information presented at the Plenary Sessions provided the 
various countries with considerable useful material for developing improved 
codes and regulations. 

Even though there appeared to be a number of problems that needed working 
on, the proposal made at the Vienna Session in 1963 to convert mine lighting 
from a Secretariat to an Expert committee was not approved by the Action 
Committee. The reasons for this were the decline in coal mining in many 
countries and the apparent difficulty of the Chairman to obtain active cooper- 
ation from the National Committees. Consequently, in 1967 the Committee was 
discontinued . 

Despite the fact that a separate group working on mine lighting no longer 
existed, there was a feeling that it should not be completely eliminated from 
the CIE technical activities. Therefore, Committee TC-4 . 1 on Interior 
Lighting was asked to look into the matter. If there appeared to be suffi- 
cient interest and full cooperation could be obtained from National 
Committees, a panel would be organized within that Committee to look after 
mine lighting. 

At about this same time the Polish National Committee on Illumination 
submitted a proposal to establish a Study Group which would have the task of 
determining if there was sufficient interest to reactivate the committee on 
mine lighting. This proposal, which paralleled one made by TC-4 . 1 , was 
approved by the Action Committee. Accordingly, a Study Group was set up under 
the chairmanship of Dr. Peret iatkowicz with the assignment of developing and 
proposing Terms of Reference and a Working Program for a Technical Committee. 
This turnabout indicated that the CIE Administration was responsive to the 
needs and desires of the National Committees and was willing to change its 
previous position. 

The new Study Group was very active and obtained the support of many 
countries. Much of the new interest in coal mining, obviously, was the result 
of the energy crisis which began to be felt throughout the world in 1973. 
Because of the strong response by National Committees, the Action Committee at 
the 1975 London Session included TC-4. 10, Mine Lighting, on the roster of 
currently active CIE Technical Committees. 

Under the chairmanship of Dr. Peretiatkowicz the Committee has made 
considerable progress since its reactivation. This was evidenced by the 1978 



15 



International Conference in Poland and the well-attended meetings at the 1979 
Kyoto Session. I should mention that the CIE Action Committee thoroughly 
reviews the work of all the Technical Committees at least once a year. The 
reports on TC-^.10, which have been summarized in the CIE Bulletin, are good 
indicators that positive progress is being made. 

According to the latest CIE Roster, 19 countries are represented on 
TC-4.10. Its Terms of Reference are: "To study the fundamental aspects of 
the lighting of underground and open-cast mining." The Working Program now 
includes : 

1. To analyze and prepare recommendations for the lighting of open-cast 
mines . 

2. The application of photometric measurements in mines. 

3. To investigate and make recommendations on personal lamps. 

4. To investigate the requirements for underground mine lighting. 

5. Terminology. 

This ambitious but attainable program is in the hands of three subcommittees. 

This brings me to the present Conference which illustrates the current 
interest in and the importance attached to mine lighting. According to pre- 
liminary information, we have representatives from at least eight countries as 
compared to five at the first Conference. The attendance certainly indicates 
the seriousness with which the many lighting and visual problems in mines are 
taken . 

While I have been deeply involved with lighting and vision research for 
more than half a century, my first real contact with mine lighting did not 
come until about two years ago. Of course, many of my research results on 
visibility and glare were pertinent to conditions in mines, but none of the 
investigations were aimed specifically at this lighting application. 

Even from my limited experience, it is evident that the lighting of mines 
involves many unique problems. Developments of machines and automated proce- 
dures have eliminated some of the back-breaking work by pick and shovel. 
However, the machines are operated by people who must be able to see. About 
everything involves movement and thus the tasks are dynamic; far different 
than a man standing or sitting at a machine in a factory. The mine worker 
must be able to see in order to accomplish his task and, more important, to be 
safe. Indeed, safety is the key word in mining. 

The machine operator and other workers in a mine need to be able to 
orient themselves in a difficult visual environment . Under the most adverse 
conditions, illumination must be provided on all mine surfaces and machines, 



16 

ideally without glare. General lighting, as in a factory, is out of the 
question. Mobility demands lighting equipment mounted on machines and 
workers. Moreover, such equipment must be durable to withstand the rigors of 
physical abuse and without introducing hazards in what may become a poten- 
tially dangerous situation. 

A review of the papers to be presented at this Conference indicates that 
just about every aspect of mine lighting will be covered. I am sure that they 
and the discussions which are sure to follow will be interesting and stimu- 
lating as well as providing considerable useful information for the members of 
CIE Committee TC-4.10. I, too, expect to learn a great deal. 

In closing this presentation, I should say a word or two about this 
meeting place. The National Mine Health and Safety Academy is a unique insti- 
tution and I cannot think of a more appropriate location for the Conference. 
It is dedicated to improving the health and safety conditions in U.S. mines. 
As such, its objectives are identical to those of the CIE. I am sure that 
when you leave this Conference you will do so with a feeling that these two 
days have been most worthwhile. 



17 



DISCOMFORT GLARE SENSITIVITY OF UNDERGROUND MINE PERSONNEL 

by 
Sylvester K. Guth l 

ABSTRACT 

A large group of underground miners adjusted the luminance of a glare 
source in a standardized visual environment to produce a sensation at the 
borderline between comfort and discomfort (BCD). The data, on the average, 
indicate that the miners are less sensitive to glare than those whose data 
were used for developing the discomfort glare rating system for interior 
lighting. 

INTRODUCTION 

Extensive investigations (l) have resulted in the development of a dis- 
comfort glare evaluation procedure for interior lighting (2). Those investi- 
gations, conducted over a period of about 20 years, involved a total of more 
than 200 observers who made subjective evaluations of a wide variety of light- 
ing conditions and systems corresponding to those encountered in offices, 
schools, and industry. A significant result of employing the large number of 
observers was the development of a Visual Comfort Probability (VCP) basis for 
rating lighting systems. This permitted expressing discomfort glare evalu- 
ations in terms of the percent of observers who would be expected to judge a 
lighted environment as being acceptable. The VCP scale was derived from the 
subjective judgments and thus represents the relative sensitivity to dis- 
comfort glare of that population sample. Furthermore, the application of the 
VCP procedure indicated that it was consistent with the experience. In other 
words, computed ratings showed that the observers as a group and in terms of 
glare sensitivity were representative of those working in offices, schools, 
and industry. 

Since the environment in mines is considerably different from typical 
lighted environments, a number of questions arise if one wants to apply the 
VCP procedure to mine lighting. An important and basic one concerns the 
sensitivity of mine personnel to discomfort glare. If a large group of miners 
exhibited the same sensitivity as the interior lighting population and also 
gave the same type of frequency distribution, the VCP procedure could be 
expected to be applicable to the mine environment. Any difference, especially 
with respect to glare sensitivity, will require some modification in the VCP 
procedure . 



Consultant, South Euclid, Ohio. 



18 

This paper is a brief summary report on that part of a more extensive 
investigation dealing with the evaluation of glare in coal mines. It is 
concerned with the sensitivity of underground miners to glare. The objective 
is to determine if those who spend considerable time in coal mines are more or 
less sensitive to discomfort glare than the population used for developing the 
Visual Comfort Probability procedure applicable to interior lighting. 

EXPERIMENTAL CONDITIONS 

Discomfort Glare Calibrating Device 

The environment in which the glare source was evaluated was a cubicle 
used in conjunction with the Discomfort Glare Evaluator (3). The cubicle was 
designed to approximate the large sphere used in the basic BCD investigations 
(4). It was 100 cm deep, 80 cm high, and 60 cm wide (40 x 32 x 24 inches). A 
head- and chinrest were positioned at the front opening so as to locate the 
eyes of the observer even with the front panel. The test source was viewed 
through a circular aperture on the horizontal line of sight in the rear wall 
of the cubicle. The size of the aperture subtended a solid angle of 0.0011 
steradian, the same as that used in the original basic discomfort glare 
investigations . 

The luminous element of the Discomfort Glare Evaluator was reflected 
toward the observer's eyes by a diagonal mirror located outside the rear of 
the cubicle. The luminance of the source, which was under the control of the 
observer, was continually variable from to 40 000 cd/m 2 (0 to 12 000 fL) . 

The interior of the cubicle could be illuminated to provide field lumi- 
nances of 3.4, 34, and 340 cd/m 2 (0.1, 1.0, and 10 fL) . The arrangement for 
providing the source luminance, being external, did not measurably affect the 
internal luminance of the cubicle. 

Observers 



A total of 115 observers participated in the investigation. However, 
incomplete or very erratic data were obtained from 14 observers and their 
results have been excluded from the analyses. 

Miners came in for testing either just before going on a work-shift or as 
they came off a shift. While workers from all the shifts were represented, it 
was not possible to obtain a complete balance. 

Procedure 

Each observer adjusted the luminance of the test source until he judged 
it to produce a sensation of the borderline between comfort and discomfort 
(BCD sensation). The source, which was viewed directly, was exposed for 
1 second intervals separated by 1 second off periods. The 1-second momentary 
procedure was developed for the original discomfort glare investigations (4) 



19 

and found to be long enough for the observer to receive the full impact of 
glare but sufficiently short so that the source luminance did not signifi- 
cantly affect adaptation. This latter point is particularly important when 
the field luminance is low. 

Each observer made a series of at least five BCD judgments for each field 
luminance. In some cases, a repeat set of observations was made with the 
34 cd/m 2 (1 fL) . About one-fourth of them made observations before and after 
the same shift, but on different days. 

RESULTS AND ANALYSES 

The geometric mean luminances judged by the 101 observers to produce the 
BCD sensation are given in the table. Also included are the corresponding BCD 
luminances computed from the Guth formula (l). The latter are from what might 
be called a typical office worker population involving more than 200 observ- 
ers . 

Field luminance 3.4 (0.1) 34 (1) 343 (10) 

BCD - miners 1216 (355) 2326 (679) 4296 (1259) 

BCD - office workers 442 (129) 1216 (355) 3351 (978) 

It is evident that the miners selected considerably higher BCD luminances 
than the office population. However, the differences are not the same as the 
three field luminances, the ratios being 2.75, 1.91, and 1.28. 

The relationships in the table can be represented by the following 
equations : 

Miners L = 2326F ' 28 (l) 

Office workers L = 1216F ' (2) 

where L is the BCD luminance of the source and F is the field luminance, both 
expressed in cd/m 2 . 

The differences in the exponents of F was surprising. All of our previ- 
ous BCD investigations have resulted in an exponent of 0.44. One of these 
investigations (5), involving an evaluation of discomfort glare from sodium, 
mercury, and filament lighting for roadways, included the same field lumi- 
nances used in the present one. Similarly, work reported by Putnam and 
Faucett (6) at low luminance levels also indicated the exponent to be about 
0.44. Other investigators (7) have reported the exponent to be between 0.5 and 
0.6. 

At present , no reason can be given for the lower exponent obtained from 
the BCD data of the miners. The experimental procedure is not suspect because 



20 

it was identical to that employed in many previous researches. The Discomfort 
Glare Evaluator is one that was used in other investigations. 

A preliminary analysis of the average BCD values obtained by the miners 
shows that the distributions are somewhat skewed. The skewedness appears to 
be approximately the same for the three field luminances. This analysis 
also emphasizes the relatively large range of BCD luminances for the mining 
population. Relative BCD luminances for the more and less sensitive groups of 
observers ranged from 8 to 634, or a ratio of 80 to 1. This compares with a 
range of 25 to 550 and a ratio of 22 to 1 in relative BCD luminance obtained 
with the office workers. The selection of somewhat lower BCD luminances by 
the miners is one reason for the skewed relationship. 

CONCLUSIONS 

The data obtained by the underground miners are considered to be quite 
good, considering that none of them had ever participated in this type of 
investigation. In most cases their results were internally consistent. Some 
BCD judgments resulted in rather low or high luminances, indicating that those 
observers probably did not fully understand the instructions. 

The higher BCD judgments of the miners as compared with the office 
workers does not seem to key in with their environmental working conditions. 
That is, because they spend their working hours in a dark environment, one 
would expect them to be more sensitive to glare. However, in a typical mine 
many miners often are subjected to rather high degrees of glare, especially 
from the lighting equipment on machines. Such exposure to glare would be 
expected to make them less sensitive and thus select higher BCD luminances. 

The results of this investigation, in terms of preliminary analyses of 
the data, lead to the conclusion that, on the average, the mining population 
is less sensitive to discomfort glare than a non-mining population. Appar- 
ently, the dark working environment does not adversely affect glare judgments. 
However, since a small but significant percent of the miners are quite sensi- 
tive to glare, it is misleading to consider only the average BCD value. When 
establishing permissible source luminances in mines it is necessary to take 
into account the more sensitive individuals. 

Further analyses of the data need to be made to determine if such effects 
as age, work shift, number of years as an underground miner, etc., have any 
influence on judgments of discomfort glare. 

The author expresses appreciation to P. D. Lindahl who did the BCD test- 
ing of the miners for the excellent manner in which he carried on the inves- 
tigation . 



21 



REFERENCES 

(1) Guth, S. K.: "A Method for the Evaluation of Discomfort Glare," 
Illuminating Engineering, 58, 1963, 351. 

(2) Committee on Recommendations of Ouality and Quantity of Illumination of 
the IES: "Outline of a Standard Procedure for Computing Visual Comfort 
Ratings for Interior Lighting," R00 Report No. 2 (1972), Journal of the 
Illuminating Engineering Society, 3, 1973, 328. 

(3) Guth, S. K. and McNelis, J. F. : "A Discomfort Glare Evaluator," 
Illuminating Engineering, 54, 1959, 398. 

(4) Luckiesh, M. and Guth, S. K.: "Brightness in Visual Field at Borderline 
Between Comfort and Discomfort (BCD)," Illuminating Engineering, 44, 1949, 
650. 

(5) Eastman, A. A. and McNelis, J. F. : "An Evaluation of Sodium, Mercury and 
Filament Lighting for Roadways," Illuminating Engineering, 58, 1963, 28. 

(6) Putnam, R. C. and Faucett , R. C. : "The Threshold of Discomfort Glare at 
Low Adaptation Levels," Illuminating Engineering, 46, 1951, 506. 

(7) Guth, S. K.: "Ouality of Lighting," Illuminating Engineering, 50, 1955, 
279. 



22 



TITLES OF PAPERS: Problems of Electric Mine 

Lighting in the Work of CIE 



Mine Underground Illumination 
in Poland 

AUTHOR: Adam Peretiatkowicz, Dr.Sc. 

Research and Development Center for 
Mining Mechanization, Electrotechnics, 
and Automation Systems 
Katowice, Poland 



Dr. Peretiatkowicz is Assistant Professor and a scientific worker with 
OBR SMEAG, having about 100 publications — including three books, about 40 
inventions, and has authored seven standards. He has been cooperating with 
CIE for over 20 years, and during the period 1959-1963, was Secretary of the 
Secretariat Committee S-3.1.5 Eclairage des Mines. Since 1957 he has been 
chairman of Technical Committee TC-4.10 Mine Lighting. 



23 



MINE UNDERGROUND ILLUMINATION IN POLAND 

by 
Adam Peretiatkowicz* 



ABSTRACT 

As a main task of this paper, the author was asked to acquaint American 
participants of the 2nd International Mine Lighting Conference with illumina- 
tion technics used in Polish underground mines. 

In the introduction is a short description of the characteristics of 
main branches of the Polish mining industry; i.e., the hard coal mining, the 
copper ore and zinc-lead ore mining as well as the rock-salt (halite) mining 
industry. 

Discussion on several illumination systems, used in various types of 
headings in Polish underground mines, have been limited to short character- 
istics of the solutions applied there. Not dwelling upon a general illumina- 
tion system of fixed headings — as chambers, galleries, etc., — greater atten- 
tion has been called to the problem of general illumination systems applied 
within preparatory faces (as sinked shafts, end gates, etc.) as well as work- 
ing faces (longwalls and sloping faces). In this chapter both general illu- 
mination systems — supplied directly from the mains — and those affected by 
means of self-propelled mining machines have been discussed. 

In the next chapters, some of the battery lamps used in Poland have been 
presented, among them end lamp, portable lamp for general illumination of a 
place of rescue action, and portable lamp for repair gangs. 

INTRODUCTION 

Mining is one of the basic Polish industries. The following amounts of 
minerals are mined by means of underground methods (according to data of 1978) 

- hard coal - 195 millions tons/year 

- copper ores - 27 millions tons/year 

- zinc - lead ores - 5,5 millions tons/year 

- rock salt (halite) - 1,4 millions tons/year 



*Dr. Sc, Assist. Prof., Research and Development Centre for Mining Mech- 
anization, Electrotechnics and Automation Systems, Katowice, Poland. 



24 

In the same year the following amounts of other minerals have been mined 
in open pit plants: 

- brown coal (lignite) - 44,1 millions tons/year 

- sulphur - 4,8 millions tons/year (partly 

using the Frash's method) 

- others, as limestones, stones, etc. 

Short characterization of the mining branches based on the underground 
exploitation methods is as follows: 

Hard Coal Mining 

Hard coal mining is of dominating importance in Poland — from the point of 
view of both annual production and employment. At the moment two hard coal 
basins are being operated in Poland: 

- Upper Silesia Basin, giving approximately 95% of the total pro- 
ductivity (from deposits located in the area of approximately 
600 sq. km). 

- Lower Silesia Basin, giving approximately 3% of the total 
productivity (mainly coking coals). 

Besides these two basins, the third one is being prepared now for exploi- 
tation, with its first mine under construction. The newest basin is located 
in the southeastern part of the country, close to Lublin city. 

In the Upper Silesia Basin the coal deposits occur almost horizontally, 
with their average thickness around 2.1 m; however, the maximum thickness 
reaches up to 21 m — in the 510 m ledge. The coal ledges occur in layers and 
in some places happen also to be separated by zinc — lead ore ledges. 

Total thickness of the hard coal ledges reaches 62 meters in the eastern 
part of the coal basin and up to 140 meters in its western part. Such an oc- 
currence of the coal ledges causes that, in particular mines, coal is mixed 
simultaneously from ledges on different depths. Presently the mines are op- 
erated on depths between 200 and 1000 meters; however, 60% of the mined coal 
comes from the ledges occurring down to 500 meters. 

The ledges under operation have a minimum thickness of 0.5 m while thick- 
nesses are exploited layer by layer, using hydraulic filling. The most popu- 
lar exploitation method is longwall (over 85% of the total productivity), 
based on the use of self-movable, mechanized mining and continuous miners. 

There are usually several longwalls within an exploitation field, having 
several hundred meters each. The coal mined by means of the continuous miners 
is loaded onto wall-type push-plate conveyors and, subsequently, is hauled by 



25 

means of belt conveyors up to the loading station. Within the station, coal 
is reloaded into hauling cars of 5 tons capacity and taken to the pit bottom. 
Skip hoists (15-30 tons) are generally used to draw the coal out to the mine 
surface. 

Copper Ore Mining 

The Polish Copper Basin, located in the Lubin-Glogow-Legnica area, has 
reached its production level placing Poland among the six world leading copper 
producers. 

The Polish copper ore mines operate on ledges having thickness of 4 to 7 
meters, occurring on the depths between 600 and 850 meters. Good roof condi- 
tions enabled introduction of the chamber-pillar exploitation system and use 
of self-propelled mining machines both in face areas and directly in their 
vicinities. In the face areas, self-propelled drill trucks, roof bolting ma- 
chines, and loaders are in a general use, supported by bulldozers and shuttle 
cars . 

Zinc-Lead Ore Mining 

At the moment, zinc-lead ores are mined mainly in the following two areas: 

- the old basin in Bytom area, Upper Silesia, giving 11% of the total 
productivity, and 

- the new basin in Olkusz area, giving 52% of the total productivity. 

In the Polish zinc-lead ore mines, both longwall and pillar exploitation 
systems are operated. Material loading is mechanized and hauling cars (4.5 
tons capacity) are used to take the material away from exploitation fields. 

Rock-Salt Mining 

Rock-salt has been exploited in Poland, in underground mines, since the 
Twelfth century. The oldest mines, being still under operation, are located 
in Wieliczka and Bochnia, southeast from Cracow. 

Rock-salt is being mined, also, in underground mines located in the Klo- 
dawa-Ino Wroclaw area (central part of the country). Besides rock-salt, potas- 
sium salt deposits are also mined in northern Poland, at the Gdansk Bay. 

MINE UNDERGROUND ILLUMINATION METHODS 

After the short characterization of the Polish mining industry, I would 
like to present the Illumination methods used in our mines. Information on 
this subject is arranged in four chapters in which illumination methods for 
headings, face areas, and preparation areas, as well as illumination equipment 
for the mining machines and individual personal and special battery illumina- 
tion systems are shortly presented. 



26 

Fixed Heading Illumination 

This group, of headings includes all types of chambers, such as machine 
chamber, workshop chamber, store chamber, main pump station, small shaft 
hoisting machines, personnel transport stations, loading and unloading sta- 
tions, as well as transportation galleries. 

As far as the chambers are concerned, network illumination is used in all 
headings in which fixed workplaces exist as, for instance, workshop chambers, 
pump stations, machine rooms, etc. 

On the other hand, the chambers in which casual work activities take 
place only, as store chambers, are also equipped with the network illumina- 
tion but switched on only during personnel stay in the workplace. 

Either discharge or incandescent light sources are used for chamber illu- 
mination systems. In case of a twenty-four hour lamp burning, discharge light 
sources and, for high chambers, mercury discharge lamps are preferred. 

Pit bottoms and their areas are equipped, usually, with fixed electric 
lighting, for high rooms (over 3.5 meters) mercury discharge lamps, and fluor- 
escent or incandescent lamps for lower rooms, according to a required illumi- 
nation level. The same applies roughly to personnel transportation stations 
as well as to loading and unloading points. 

Cross-cut and transportation gallery sectors, provided either for material 
hauling or pedestrian traffic, are equipped with fixed lighting systems, if 
traffic intensity proves it necessary under the respective Polish Standard 
(PN-73/G-02600) . For illumination of such galleries, fluorescent lamps are 
preferred. Gangways provided for material transportation only, with pedestrian 
traffic prohibited, generally are not equipped with a network illumination, ex- 
cept cross-roads, junctions, and other places where hazardous conditions exist. 

As it appears clearly from this presentation, on particular exploitation 
levels, network illumination exists in specific mine sectors, usually very dis- 
tant from each other. Consequently, power supply for the lighting installa- 
tions, grouped on small areas, is provided usually by means of small, 3-phase 
transformer illumination units of 1.6 up to 10 kVA and a range of an illumina- 
tion network supplied from a unit does not exceed 250 meters. For gangway il- 
lumination, the 3-phase transformer units are generally spaced every 800 meters. 

Preparation Heading Illumination 

Discussing this subject, I would like to call your attention, gentlemen, 
to the problem of illumination of a sinked shaft bottom and. later on, to the 
problem of illumination of end gates, blast mined in both coal and stone. 



27 



Illumination of a Sinked Shaft Bottom 

A movable working platform, suspended 15 up to 40 meters over the bottom 
of a sinked shaft, gives a base for electric power supply for the equipment 
used in the shaft sinking operation. The platform is utilized also for light- 
ing the shaft tube underneath the platform as well as the shaft bottom. This 
lighting is arranged by means of two mercury-vapor reflector lamps of LFRF 
type, having power of 250 or 400 watts. These lamps are mounted on the plat- 
form lower section and protected against blasting consequences by 90 degrees 
tilt. 

Such a solution assures obtaining a minimum illumination level on the 
shaft bottom of 20 luxes, according to requirements of respective standards in 
force. Obviously, in a zone which is not darkened by the operating equipment 
(as loader or other auxiliary machines), at normally applied height of the 
platform (approximately 20 meters above the shaft bottom) the obtained illumi- 
nation level is considerably higher. The power supply unit mounted on the 
platform is supplied with 500 volts tension from the surface by means of a 
self-supporting shaft- type cable. 

General Illumination System for Non-mechanized Heading Faces 

In case of headings driven in stone, where, in majority, only compressed 
air is supplied, the only solution is application of turbine-type air lamps. 
The turbine-type lamps LTR-3, being produced now in Poland, are adapted to 
this particular purpose. They are equipped with mercury discharge lamp LRF-80 
(80 watts), with corrected light spectrum, and give satisfactory strong lumi- 
nous flux, approximately 3000 lumens. Rotational reflectors installed on the 
lamp enable the working personnel to direct the flux in a desirable direction 
and to protect themselves against glare. 

To illuminate the face background zone, LTR-3 lamps should be mounted 
only, with spacing of up to 10 meters. In locating the lamps, attention 
should be paid to install them in such a way that satisfactory illumination of 
work places is provided. In case of electric power supply to the face, both 
mercury discharge lamps and incandescent or fluorescent lamps could be used 
for illumination. 

According to the safety code, the mercury lamps over 125 watts and incan- 
descent lamps over 150 watts must not be suspended lower than 2 m above the 
floor level, provided that they are equipped with special glare protective 
screens. 

Before firing (blasting), all lamps exposed to striking should be removed 
from the hazardous area. It can be assumed on practical basis that in case of 
a heading driven in coal, the striking distance does not exceed 20 meters while 
in case of a heading driven in stone the distance is approximately 30 meters, 
counting from the front face. 



28 

Network Illumination System for Longwalls 

Illumination Systems for Longwalls 
with Self-advancing Roof-support System 

During the last years in the coal mining industry the predominating equip- 
ment was longwalls with self-advancing roof support system, mined by continuous 
miners. Applied illumination systems for such longwalls depend principally on 
their heights and types of roof support system. 

In case of longwalls up to 2.0 meters high, multif luorescent lamps of OS 
2 x 13 or Swit types are used. These lamps are supplied in 3-phase systems 
and mounted under roof-bars and, in case of lower longwalls, sometimes also 
between props, on the border of I and II fields. 

For higher longwall illumination, use of mercury vapor lamps of 125 or 
80 watts is widely preferred. Two types of the lamps are commonly used, one 
with the ballast built in, and the other with the ballast in a separate cas- 
ing. The latter solution enables illumination of higher longwalls by means of 
lamps supplied by stub cable from the 3-phase main line. 

To facilitate correct longwall illumination in underground mines, a spe- 
cial diagram has been elaborated. The diagram shows maximum spacing between 
the lamps, separately for various types of the lamps and in relation to the 
longwall heights. 

Illumination System for Longwalls with Individual Supports 

Operation of longwalls with individual roof supports is nowadays very 
rare in the coal mining industry while still and often applied in ore mines. 
Principal obstacle met at introduction of network illumination is a necessary 
relaying (moving) of a system, following the longwall advance. In case of 
lower longwalls, difficulties and strenuousness of jobs involved make prac- 
tically unattainable the profits expected from general illumination systems. 
Consequently, the longwalls in lower ledges are rarely equipped with general 
illumination. On medium and higher longwalls, relaying is almost universally 
put into practice. In such cases, the mine crews prefer, rather, incandescent 
lamps because of their simpler construction and considerably smaller weight. 
These lamps are fed either directly from the main line or from a stub cable. 
The latter solution is willingly used on longwalls operated with hydraulic 
filling since the main line is installed along the scaled stopping and relayed 
jointly with it, once every few shifts. 

All the longwalls, regardless the type of roof support applied, are 
equipped with signalling lamps of LU-40 type, mounted directly onto push-plate 
conveyors. 



29 



Individual Lighting for Mining Machines 

Face Machines 

The most typical for this group is a continuous miner. The problem of 
its lighting equipment has not yet been solved satisfactorily. Polish-made 
combined mining machines, either longwall or gallery type, are equipped with 
incandescent projectors, illuminating the operated section of the wall. Such 
a solution is considered inadequate and studies are continuing leading to 
modernization of the lighting equipment for the said machines. The first long- 
wall continuous miner equipped with 8 W. fluorescent lamps was commissioned in 
Poland in February, 1972. The lamps built on it ensured general lighting of 
work places of machine personnel. 

Self-propelled Face Machines 

Self-propelled face machines used in Poland are equipped with both their 
movement route lighting and their working place illumination. Examples of ap- 
plied solutions are shown on sketches of gadding car, loader, and anchoring 
machines. Another solution has been used for illumination of a pneumatically 
driven gadding car, where turbine reflector LTR-3, with 80 watts mercury dis- 
charge lamp, has been installed. This assures sufficient illumination of the 
whole face area. 

Other self-propelled face machines have, for the time being, no possibil- 
ity of sufficient illumination of the entire face area. 

Mining Battery Lamps 

In this chapter I would like to present briefly some of the solutions of 
mining battery lamps used in the Polish mining industry; namely, cap lamp RC-12 
and lamp OP-1 for underground trains, portable LRS-3 lamp for rescue workers, 
as well as portable lamp for repair gangs. 

Cap Lamp RC-12 

Since a few years the RC-12 cap lamp has been introduced as an essential 
equipment of Polish miners. The lamp is equipped with a 3-cell cadmium-nickel 
battery (12 Ah, 3.6 V) and a bifilament bulb of 3.6 watts. Its luminous flux 
after 8 hours of continuous operation must not be lower than 20 lumens. Cas- 
ing of this lamp is made from polycaproamid . Gross weight of the lamp is 2.4 
kgs . The lamp is adapted for self-service charging system at constant voltage. 
Lamp rooms are equipped with 102-stand chargers. 

End Lamp OP-1 

This lamp is used to indicate the end of an underground train and has been 
shown on the drawing. The lamp is based on the same battery as used on the 
above-mentioned cap lamp RC-12. Additionally, it is equipped with a special 



30 



head and a red bowl. This lamp is mounted on the last train car but is visi- 
ble also from the front and locomotive. Battery charging is performed in a 
typical charger for the cap lamps RC-12. 

Portable Lamp LRS-3 

This lamp is provided for general illumination of a place of rescue ac- 
tion, in nonmethanic and methanic headings of low and high coal beds. 

Operation principle of the lamp is the following: the current source of 
the lamp forms a battery of 8 RF type floating cells. The battery, capable 
only for a single use as a current source, requires no charging and a full 
electromotive force is obtained within several seconds of its immersion in an 
electrolyte made of sea water or, as a substitute, of an aqueous domestic salt 
solution with a concentration of approximately 3.5 percent. The battery, 
stored in a dry condition in a protective bag, does not lose its electro- 
chemical properties during a period of at least three years. Starting of the 
lamp takes place through inserting the battery into a container, connecting 
the battery conductors with the light source, and then floating the battery 
with electrolyte and closing the lamp cover. The lamp reaches its full burn- 
ing capacity within 100 to 150 seconds from the moment of connecting the cur- 
rent source with the light source. After each discharge of the battery, prep- 
aration of the lamp for further use requires replacement of the used battery 
and electrolyte by a new, fully efficient battery and fresh electrolyte. 

The lamp is provided with a wide-angle projector with an adjustable light 
distribution angle and a 15 watts incandescent lamp. The projector, movable 
in vertical direction, is fixed on the lamp cover by means of a metal tube. 
Inside the tube there are electric conductors connecting the incandescent lamp 
with the current source. Extension of the tube forms a lamp holder designed 
for carrying of the lamp in one hand. As a current source for this lamp, a 
battery of 8 floating cells of RF type, connected in series, activated by 
means of sea water, has been applied. The battery is housed in a container 
forming simultaneously the lamp base. For suspension of the lamp on the lin- 
ing, a hook is fixed at the lamp holder. The explosion-proof casing of the 
lamp has been designed according to Polish standard. Total mass of the lamp 
amounts to approximately 8 kgs. 

Lamp's luminous parameters: 

- rated luminous flux - 220 lm 

- lamp's true luminous flux - 140 lm 

- light distribution angle - adjustable from 12° to 30° 

- lamp's burning time - 8 to 10 hours. 



31 



Portable Lamp for Repair Gangs 

Needs of mining crews are not limited to portable lamps Illuminating 
locale of a rescue action. Also* repair gangs need to use a similar lamp to 
illuminate areas of their activities. 

Because of respectively high costs of reserve batteries in LRS-3 lamps, 
an alternative design of the lamp is being prepared, based on a typical cadmium- 
nickel battery. Lighting parameters of this alternative solution would be kept 
unchanged; however, burning time would have to be reduced to 5 hours and weight 
of the lamp would increase about 4 kgs . 

SUMMARY 

Because of the time limits for presentation of the papers, this elabora- 
tion could not exhaust the subject of underground mine illumination in Poland. 
Nevertheless, its task will be fully secured if participants of the 2nd Inter- 
national Mine Lighting Conference form for themselves a judgment on the state 
of Polish techniques of underground mine illumination. 



32 



PROBLEMS OF ELECTRIC MINE LIGHTING 
IN THE WORK OF CIE 

by 

Adam Peretiatkowicz* 



ABSTRACT 

The paper describes first attempts in introducing electric lighting into 
the mines. Development work on illumination was since 1900 coordinated by 
International Commission on Photometry, which in 1913 transformed into the 
"Commission Internationale de l'Eclairage" /CIE/. 

CIE included the problems of mine lighting in its work in 1931, estab- 
lishing the Study Committee 29 "Mine Lighting." The paper characterizes the 
development of the work on mine illumination within CIE during the last 40 
years. 

Last of all, the present state of the work of Technical Committee TC- 
4.10 has been described, giving also some attention to the events organized 
by the Committee, as well as to its plans for the next years. 

Implementation of the Electric Light into the Mines 

In 1861, the first project of a mining electric lamp was worked out 
[1,2] Benois and Dumas, two Frenchmen, constructed portable electric lamp. 
It consisted of three main parts: zinc-carbon element, Ruhmkorft induction 
coil, and Geissler pipe. The Geissler pipe was giving a weak reddish light 
at current flow. In comparison with oil lamps, used then, the luminous flux 



1 Dr. Sc, Assist. Prof., Research and Development Centre for Mining Mechan- 
ization, Electrotechnics, and Automation Systems. Katowice, Poland. 



33 

of this lamp was 6.5 times weaker. By reason of that, this lamp could not be 
kept in use. 

The first mentions of the use of electric light in mines refer to arc 
lamps installed aboveground. In 1879, electric lighting was introduced in 
Matylda Colliery in Swietochlowice. In the periodical "Zeitschrift fur das 
Berg-Hutten und Salinenwessen" 3 of 1880 the information could be found that 
the East Field of the Matylda Colliery, the draving shaft bank and a part of 
the sorting plant had since been illuminated with electric lamp. Current was 
provided by the alternator with exciter, of Siemens-Halske, Berlin, for 4 arc 
lamps. These 4 arc lamps equipped with alabaster globes replaced 34 big 
kerosene or oil lamps used before in those rooms. 

Practical application of arc lamps in the underground of collieries was 
difficult because of the hazard of methane mixture explosion or the ignition 
of coal dust suspension. 

It was not until incandescent bulbs were developed and manufactured that 
the introduction of electric light underground became possible [4], W. H. 
Uhland [3] wrote in 1884 in his book, "Das Elekrishe Licht" : "Another domain 
in which incandescent light has found wider and wider application is mine 
lighting, where it is not only used to achieve sufficient lightness, but also 
to avoid the ignition of explosive mixture. 

The incandescent light may be used for these purposes provided it is 
prepared for this by sufficient protection of the wires, the connections of 
which must exclude the possibility of sparking." A mine lamp has been con- 
structed by Crompton/England/ using Swan bulb with a carbon filament. He 
closed the incandescent bulb tightly in an additional globe made of strong 
glass which he has protected with a protective grid of metal bars. Edison 
closed his mine lamp in a tight vessel with water. /In our country it is 
not possible to find any draft of this solution/. 

In British mining industry, first trials of incandescent lamps [5] took 
place in 1881. In 1883, 20 Swan lamps were installed at a colliery in South 
Wales feeded from a Gramme generator /50 V DC/ located at the shaft bottom. 
All lamps were connected in series in a single circuit. 

At the oldest Polish Salt Mine in Wieliczka - being in exploitation for 
8 centuries, the electric lighting for mine shafts was introduced in 1881 [6]. 
In Silesia the first installation with incandescent lamps was built in 
Szombierki Colliery in By torn in 1882. 

International Commission on Illumination - CIE 

The history of CIE is closely related to the development of science in 
the field of lighting. The beginning of their activity is connected with the 
Paris World Exhibition in 1900, when the International Gas Industry Congress 
under the chairmanship of Th Vantier, professor of the Lyon University, 



34 

decided to establish an international association which would initiate 
photometric study of gas burners used for illumination. 

In this way the International Commission on Photometry was established. 
Soon after that, the growth of electric lighting has forced the Commission to 
extend their activities to the problems connected with the construction and 
manufacturing of electric light sources, as well as their practical 
application. 

As the result, during the Commission's Session in Berlin in August 1913, 
the resolution was taken establishing the "Commission Internationale de 
l'Eclairage" CIE/lnternational Commission on Illumination/which was to con- 
tinue the works in the field of lighting measurements initiated by the Inter- 
national Commission on Photometry and additionally take up new problems con- 
nected with the introduction of the new electric lighting into practice. 

The activity of the CIE in the field of science and technology is based 
on the studies of the Technical Committee's TC and Study Groups SG, each of 
them having appropraite activity range assigned. At present, there are 26 TC 
and 1 SG acting within the CIE. 

Twenty-nine countries participate in the CIE and 9 other countries have 
a status of the associate members. 

CIE Work on Mine Lighting 

Problems of mine lighting became of interest to CIE not before 1931. 

In September this year, the 8th Session of the CIE took place in 
Cambridge. At that session the individual paper was presented by W. Maurice 
/GB/ : "A Standard of Illumination for Mines" and after discussion the reso- 
lution was taken to include mine lighting in the CIE studies. 

As a consequence, Study Committee 29 "Mine Lighting" was established, 
the secretariat being allocated to Great Britain [7]. The terms of reference 
of the new Study Committee were defined as follows: "to study the regulations 
and methods used in the lighting of coal mines /personal and general light- 
ing/". 

The Committee prepared an international enquiry sheet with questions to 
the construction of the mine lighting equipment, its application, obligatory 
regulations, etc. Replies to this enquiry were received from 8 countries. 

In July 1935, the 9th Session of the CIE took place in Berlin and 
Karlsruhe. An extensive report of the Committee, including a detailed analy- 
sis of the answers obtained from the 8 countries, was presented [8] and the 
working program of the Committee, for the next period, was somewhat widened. 
The most important tasks were to obtain measurements of illumination in the 
mines of the member countries, and to study the influence of illumination 
and glare on efficiency and safety. 



35 

For the next quadrennium 1935-1939, the responsibility for the Committee 
was committed to Germany. In 1939, the 10th Session of the CIE was held in 
Scheveningen, Holland. The Committee presented a report [9] and individual 
papers were presented, such as: "Illumination and miner's nystagmus" by 
J. Wellwood-Ferguson /GB/ and "Changing requirements and lighting factors for 
coal and metal mining in USA" by Carl E. Egeler /US/ and "Stand und 
Entwicklungsmoglichkeiten der Beleuchtung in Schlargwettergeschiitzten 
Steinkohlengruben" by K. Nehring /D/. 

The 11th Session of the CIE took place in 1948 in Paris. The report pre- 
pared on the basis of the enquiry launched in 1947 was presented, and an 
individual paper entitled "Fluorescent Lighting in Mines" was given by Dr. 
F. W. Scharplay and R. Crawford /GB/. Belgium took over the secretariat for 
the next period /1948-1951/. 

The 12th Session of the CIE took place in 1951 in Stockholm. Individual 
papers were presented: "Dark Adaptation and Miner's Nystagmus" by J. W. 
Ferguson and F. W. Scharpley /GB/ "Problems Associated with Underground 
Lighting in British Coal Mines," by D. Strachan /GB/. Official CIE recommen- 
dations agreed at the 12th Session advised the Committee. 

1. To work on the determination of: 

- the visibility level required by different works in mines 

- the possibilities of reducing glare and of improving the visual 
conditions underground by whitening dark surfaces or by spray- 
ing them with bright stone powder 

- the economical profits arising from the introduction of light- 
ing related to the amount of coal excavated and to the costs 
of labour 

- the glare coefficient at the illumination levels obtained at 
that time at the underground works 

2. To ask the National Committees to prepare practical recommenda- 
tions for analysis and comparison at the next CIE Session. 

In 1951, as part of a reorganization of the CIE, the Mine Lighting Com- 
mittee became Secretariat Committee 3.1.5. with Belgium as Secretariat 
Country. 

The 13th Session of the CIE took place in Zurich. As well as a Secre- 
tariat Report, the following papers were discussed: 

a. J. Patigny /B/: ftude sur la visibilite dans les mines 

b. W. J. Wellwood Fergusson /GB/ : Darka adaptation and miner's 

nystagmus 



36 

C. W. Young /GB/: E. L. Potts, W. B. Bell /GB/: Lumen method 

of design for mine lighting installations. 

The Secretariat remained with Belgium for the next period, 1955-1959. 

At the 14th Session of the CIE in 1959 in Brussels, a report on the tech- 
nical progress in mine lighting in Poland, presented by the Polish Mine Light- 
ing Committee, raised considerable interest and the Secretariat was 
transferred to Poland for the period 1959-1963. 

The 15th Session was in 1963 in Vienna. A proposal to change from a 
Secretariat to an Expert Committee did not meet with the approval of the CIE 
Action Committee. The determining reason for this refusal was the regression 
in coal mining at that time in West Europe and USA. The Secretariat was 
committed to Great Britain for the years 1963-1967. 

The 16th Session of the CIE took place in Washington. As well as a 
Secretariat Report, the following papers were discussed: 

- W. B. Bell and I. Lewin /G.B./ "The Application of Photographic 
Photometry to the Lighting of Tunnels" 

- A. G. Neil /G.B./ "Features of the Modern Miner's Lamp" 

In this Session the Action Committee decided to include the Secretariat Com- 
mittee S-3.1.5 into the new Expert Committee E-3.1.2. Interior Lighting. So 
the Secretariat Committee S-3.1.5 Mine Lighting was discontinued. 

Technical Committee TC-4.10 Mine Lighting 

In June 1971 during the 17th Session in Barcelona, Dr. A. Peretiatkowicz 
submitted the proposal for establishing a Study Group to deal with the prob- 
lems of mine lighting. The Board of Adminsitration of the CIE considered 
this and consulted the National Committees. The increase in coal production 
was again of interest and underground mining became once more a growing 
industry. 

In September 1975, at 18th Session of the CIE in London, the Polish pro- 
posal of Barcelona was accepted and the CIE Board decided to establish 
Technical Committee 4.10 "Mine Lighting" with Poland taking the lead. 

TC-4.10 started its activity at the end of 1975; in this time 16 coun- 
tries have designated their representatives for collaboration within the 
Committee. 

The first working program of the Committee has been approved by the CIE 
Board of Administration in 1976. Its main task was to prepare international 
recommendations for the underground mine lighting, to make a worldwide survey 
of mine lighting practice, and to prepare mine lighting vocabulary comprising, 
terms and their definitions. 



37 

The first TC-4.10 meeting in which participated 12 delegates from 5 
countries, was held on 2-3 October 1978 in Jaszowiec /Poland/. 

At the meeting the terminology of mine lighting for the 4th edition of 
the CIE was accepted and the initial data for the international recommenda- 
tions of underground mines lighting were discussed and coordinated. 

It has been decided to establish a Subcommittee on lighting measurement 
in mines and to organise the next International Conference on Mine Lighting 
in 1981. The work of the Committee connected with preparation of the 19th 
Session of the CIE in Kyoto was also discussed. 

This meeting was joined with First International Conference on Mine 
Lighting held on 4-5th October 1978 in Jaszowiec. In the Conference took 
part 180 persons and there were presented 16 papers which referred to mine 
lighting technology in the United States, France, Belgium, Czechoslovakia, 
and Poland. Approved at Jaszowiec - 45 terms with definitions, in five 
languages, within the range of mine lighting were submitted at the meeting of 
TC-1.1 "Terminology" in Paris on 22nd November 1978. After discussion, 21 of 
them were accepted to be included into the 4th edition of the CIE as an 
additional sub-chapter "Mine Lighting." 

The second TC-4.10 meeting was held in August 22-23, 1979 during the 
9th CIE Session in Kyoto. In meeting, 22 delegates from 12 countries took 
part. At the meeting, the Chairman presented the Quadrennial Report of 
TC-4.10, which after discussion, was approved. 

In this report the scope of activity and working programme of the Com- 
mittee for the quadrennium 1975-1979 were given. There was also discussed 
the work connected with organization of the Committee with emphasizing the 
frequent fluctuations of its consitution. 

Furthermore, the report included work of the Committee proposed for the 
next quadrennius, the bibliography comprising the years 1971-1979 and a brief 
discussion of the more essential directions of work being conducted in 
world's mining for improving illumination in underground mines. 

At this meeting, Dr. A. Peretiatkowicz presented his paper: "Examination 
of Perception Level in the Conditions of Mesopic Vision." This paper con- 
tains the results of examination of perception of black-white and colour 
tests plates, carried out by the author in photometric laboratory. The test 
plates were selected to meet the needs of an underground miner and illumina- 
tion conditions, as well as the values of coefficient of reflection, were 
chosen to correspond as much as possible to the conditions of underground 
workings in hard coal mines. 

The results obtained have allowed to determine minimum luminance levels 
indispensable for safe and efficient work of the miners being employed 
underground. 



38 



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40 

The third TC-4.10 meeting, in which participated 18 delegates from 9 
countries, was held on 21-22 April, 1980 in Kokotek /Poland/. During this 
meeting, 3rd draft of the CIE Recommendations for underground mine lighting 
was discussed. Next, the following projects were submitted to be discussed: 

- further work on mine lighting terminology - accepted to be published 
in the TC-4.10 Report, 

- working programme of the Subcommittee SC-4.10B Open Cast Lighting 

Prof. Trotter presented an example of Canadian experiments regarding 
light sources. They wanted to change the tungsten filament bulb to a quartz 
hilide bulb and felt this would be a great breakthrough in cap lamp design. 
After discussion on this subject, the Chairman proposed to set up a new Sub- 
committee SC-4.10C Mine Light Sources, led by Professor Trotter. This propo- 
sition was approved and new subcommittee established. 

At this meeting, and as well at the 2nd International Conference on Mine 
Lighting, the collaboration with other Technical Committees and the programme 
of the 4th meeting of TC-4.10 planned to take place in Beckley, U.S., in 1981 
were discussed. 

The 3rd TC-4.10 meeting was joined with the International Symposium, 
which took place at the Mining Museum in Zabrze and was devoted to a hundred 
years of electric lighting in Silesian collieries. The history of electric 
lighting in underground mines, presented at the Symposium, was completed by 
the displays [in the Museum] of old lamps and new mine lighting equipment by 
Poland manufacturers. 

In Table 2 the present membership of TC-4.10 is shown. As well, the 
participation of the National Committees in the TC-4.10 work is made evident. 

The 4th TC-4.10 meeting will be organized by the U.S. National Committee. 
It will be held in Beckley, WV, in October 12-13, 1981, and will be joined 
with the 2nd International Conference on Mine Lighting, October 14-15, 1981, 
and displays of lighting equipment by U.S. manufacturers. 



41 



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Reference 

1. Bulletin Sociale Industrie Minerale, To IX - 1863 - p. 5 

2. B. Rudnicki: Historial Outline of the development of personal lamps in 
mines - International Mine Lighting Conference, Conference Proceedings, 
part I, Jaszowiec /Poland/ October 4-5, 1978 

3. Versuche und Verbesserung bei dem Bergwerksbetriebe in Preussen wahrend 
des Jahres 1879, Zeitschrift fur das Berg-Hutten und Salinanwesen, 1880 - 
p. 237 

4. B. Rudnicki, A. Peretiatkowicz : Au outline of the development of light 
sources in mining, Proceedings of the Symposium "100 years of electrical 
illumination in Silesian collieries" Zabrze, 23rd April 1980 

5. W. H. Uhland: Das elektrische Licht, Verlag von Veit Comp. Leipzig 1884 

6. K. Guthrie: The history of lighting in the coal mines, Mining Technology 
March and April 1973 

7. Elektryczne oswietlenie szybow kopalnianych w Wieliczce, Inzynieria i 
Budownictwo, 1881 - str. 71 

8. Mine Lighting in the work of CIE, CIE Bulletin No. 36, April 1979 

9. TC-4.10 ficlairage des Mines - Rapport Quadrennial - Proceedings 19th 
Session, Publication CIE No. 5 - 1980 

10. A. Peretiatkowicz: Mine Lighting in the works of CIE and Polish Committee 
on Illumination, Proceedings Part I - International Mine Lighting Confer- 
ence, Jaszowiec October 4-5, 1978 

11. CIE Neuvieme Session Berlin et Karlsruhe - Juillet 1935, Recueil des 
travaux et compte rendu des seances, Cambridge - at the University 
Press - 1937 

12. Internationale Beleuchtungskommission, Zehnte Tagung, Scheveningen, 
Juni 1939 - Wien 1942, Band I-Sekretariatberichte, Band II - Vortrage 

13. A. Peretiatkowicz: Le probleme de l'eclairage des mines dans le cadre des 
travaux de la Commission Internationale de l'Eclairage, Lux No. 103 

Juin 1979 

14. A. Peretiatkowicz: Examens de la perceptibulite dans les conditions de la 
vision mesopique, Proceedings 19th Session, Publication CIE, No. 5 - 1980 



44 



TITLE OF PAPER: 



Modern Underground Lighting Techniques. 
New Material Which the Lighting Fittings 
Consist of; Suitable Constructions and 
Practical Testing 



AUTHOR: Ing . Georg Pawlowski 

Messrs. Adolf Schuch KG 

Worms am Rhein 

Federal Republic of Germany 



Mr. Pawlowski has been responsible for the development and construction 
of explosion proof and mine-gas-proof fittings at Messrs. Adolf Schuck KG, for 
14 years . 



45 



MODERN UNDERGROUND LIGHTING TECHNIQUES 

NEW MATERIAL WHICH THE LIGHTING FITTINGS CONSIST OF; 

SUITABLE CONSTRUCTIONS AND PRACTICAL TESTING 

by 

Ing Georg Pawlowski 1 



ABSTRACT 

The modern highly developed technics at the working place are more and 
more prevailing and consequently demand requirements of the lighting technics 
which are still higher as far as mining is concerned. The very difficult 
underground working conditions are the major reason for this development. 

Good lighting proportions are most essential for increasing the pro- 
ductivity. 

For effectively avoiding any demolition of the lighting equipment by 
mechanical or, above all, by chemical influences (corrosion), new materials 
have been created and meanwhile already tested over long periods. The hous- 
ings of lighting fittings which are made of glass fibre reinforced polyester 
have proved a success for instance with regard to chemical influences in the 
mine existing there from nature in combination with the synthetic chemicals 
additionally brought-in such as antidust pastes, increased possibility of 
corrosion - see detailed explanation. 

As a matter of fact the enormous mechnical demands have been taken into 
consideration with regard to plastic lighting fittings. 

The danger of a possible ignition of explosive methane (CH^) mixtures as 
a result from an electrostatic charge through the combination of plastic hous- 
ings and the dust particles accelerated by the ventilation has meanwhile been 
scientifically investigated during a special research program by the Institute 
for Explosion-proof ness and Explosion Technics. 

The results which are available will be explained verbally. 

Improvement of the drift lighting, 

lighting fittings for 2 x 65 W fluorescent tubes, 

photographs and explanations; 

uniform electricity supply systems; 
adjustment of the supply voltage for machines, 
appliances and lighting fixtures, 500 and 1000 volts. 

cold cathode fixtures, supply voltage 1000 volts 
in the mining, shock-proof, shot-proof; 

1 Messrs. Adolf Schuch KG, Worms am Rhine, West Germany 



46 

visual projection 

visual projection of ab. 20 - 25 diapositives of new 
floodlight systems of a very high luminous efficiency. 
Such floodlights are suitable for drill carriages, mining 
machines, locomotives and stages as well as for TV monitoring 
of automatic loaders, filming, etc; 

Report on projected lighting systems of the enclosure 
"Sch" i or new "Ex" I i, for instance several small luminaires 
connected with a supply unit of high frequency voltage (not 
yet ready for mass production) . 

INTRODUCTION 

In contrast to the previous lectures given, the basis of which has been 
the science, I would like to call your attention to a subject which seems 
to be a bit more concrete than the others. 

You know, before talking about the direction of light, the measurement 
of light or even about underground glare and reflection, we first have to see 
to it that the necessary preconditions are fulfilled. 

And this is what I am intending to talk about today. 

MODERN LIGHTING TECHNIQUES, 
MATERIALS, CONSTRUCTION AND TESTING 

The modern highly developed technics necessarily are more exacting, as 
far as the technical side of the underground lighting is concerned, since 
above all mine working is possible only under very difficult conditions. 

Due to the enormous quantity of dust resulting from drilling work and 
from shooting and blasting, as well as because of the dust near coal and stone 
cutting machines, it is imperative that the lighting equipment is optimum and 
that its functioning is excellent so that an economic winning is guaranteed. 

The following figures illustrate floodlights which have been developed 
particularly for this field of application. 

Figures 1 and 2 show a fixture using lamps, which are of the type already 
used by the motor car industry, are tungsten halogen lamps having a particu- 
larly strong filament that is positioned in a very short distance. There are 
two such lamps of 24 volts, 70 watts, arranged in series in one floodlight 
housing. The supply voltage being 42 V, the lamps are operated with under- 
voltage, which fact is very advantageous for their life. It will be 3 to 5 
times as much as the usual life of this type of lamp; the halogen circulation 
will not be impaired. 



47 





FIGURE 1. - Front view of tungsten halogen floodlight 



48 





FIGURE 2. - Junction box on rear of tungsten 
halogen floodlight. 



49 

Lighting fixtures of this type have proved best for fixation on winning 
machines. Originally, the standard incandescent lamps had to be replaced up 
to five times per shift, whereas the aforesaid tungsten halogen lamps have 
had a life of four months already, although the machines worked 18 hours per 
day. 

Larger floodlights of the simular design are also available for lamps up 
to 1000 watts. Figure 3 illustrates these floodlights on a mining machine. 

The housings of these lighting fixutes are made of a selected aluminium 
alloy. 

In future this will no more be possible. According to the New Recom- 
mendations EN, it has to be brass. 

The construction of such machines allow the fixation of lighting fittings 
which are bulky to such a degree. 

As to the shield-type support, however, the construction of the light- 
ing fixtures had to be suited to the prevailing mechanical conditions. Even 
if the shield is lowered, the construction of the luminaires must not all be 
troublesome. 

In order to meet the requirements of illumination, such lighting fixtures 
have to be arranged in small distances (Figure 4). 

Figure 5 shows a longwall face with shield- type support. 

These luminaires, the housings of which preferably are made of sheet 
steel, have been equipped with cold cathode lamps for several years: 

a. in order to increase the luminous efficiency and 

b. in order to have a sturdy lamp mostly of the Meander shape, the life 
of which is very long. 

These lighting fixtures have meanwhile been constructed such that the 
lamp and the ballast which represent one only unit (encapsulated by means of 
silicon caoutschouc or another similar product) can be exchanged very easily 
without having to switch off the light. 

The cover of the fixtures is made of transparent polycarbonate (Makro- 
lon) ; thus, any destruction through stoning or the like is avoided. 

The parts employed being injection moulded ones, the advantages of this 
method of production have, of course, been very useful by providing the inside 
of the parts with a prismatic structure opposing a relative glare. 

Due to the fact that by far not yet all longwall faces have been equip- 
ped with shield-type supports, the proved incandescent lamp (Figure 6 and 7) 



50 




FIGURE 3. - Tungsten halogen floodlights mounted 
on mining machine. 




FIGURE 4. - Lighting fixture designed for use on 
shield-type longwall supports. 



51 





FIGURE 5. - Application of shield-type lighting 
fixtures on longwall face. 






52 





FIGURE 6. - Incandescent fixtures for underground 
applications. 



53 





FIGURE 7. - Applications of incandescent-type 
lighting fixtures. 



54 




FIGURE 7 (Continued). - Applications of 
incandescent-type lighting fixtures. 



55 

fitting made of grey cast iron is still used, and of course, also the com- 
paratively short fixtures for 2 x 20 W fluorescent tubes are installed 
(Figure 8 and 9) . 

Their housings are mostly made of polyester but sometimes they are also 
made of sheet steel. You can say that lighting fixtures for fluorescent tubes 
are the most advantageous kind of illumination as far as the economical side 
is concerned. 

Even lighting fixtures for 2 x 40 W are installed, if longwall faces of 
large sizes have to be illuminated, and recently 2 x 65 W tubes have been 
employed because of their considerably higher luminous efficiency (Figure 10) . 

In the course of the past years, it has been found out that lighting 
fixtures with housings of polyester resin reinforced by glass fibre mats, are 
much more resistant to mechanical and to chemical dangers than the fixtures 
with sheet steel housings. 

Chemical products available in the mines are an increased danger of 
corrosion for all metallic parts in combination with synthetic additional 
ones, such as antidust compounds. 

Glass fibre reinforced polyester (GFUP) is extremely well suitable for 
usage in corrosive underground atmospheres. One does not know any case at 
all, neither of decay nor of decomposition of polyester products, resulting 
from chemical reactions. 

The application of several impregnated glass fibre mats consisting of 
several layers represents a sort of reinforcement that makes the mechanical 
stability of these housings equal to that of sheet steel housings at a very 
high modulus of elasticity (E = 8000 N/mm 2 ). 

In this connection I still wish to mention that this kind of material 
has got a very high tracking resistance and that consequently it is well suit- 
able for carrying various potentials (for example: inserted connection ter- 
minals) . 

KA = 380 V, determination of drop number up to short circuit; leak 
trace 

KB = determination of voltage at 50 drops maximum. 

The dangers of a possible ignition of explosive methane gas mixtures as 
a result of an electrostatic charge, through the combination between plastic 
housings and dust particles accelerated by the ventilation, have meanwhile 
been scientifically investigated on the occasion of a special research pro- 
gram. 

The institute for Explosion Proofness and Shooting and Blasting Technics 
in Dortmund, Germany, has found out - when effecting numerous experiments - 



56 




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58 

that the energy of a possible charge will not be sufficient to ignite any 
mixture of good ignition quality even under the most favourable conditions. 

Consequently, you can say that furthermore there are all possibilities 
of using without any restriction products which are made of this kind of 
material. 

Another innovation with regard to the lighting engineering is the accom- 
modation of the lighting fixtures and of their inner components to the supply 
voltages of 500 and of 1000 V prevailing in mines. For that purpose the 
lighting fixtures for fluorescent tubes are equipped either with additional 
transformers or, with special ballasts having incorporated transformers which 
can be switched over from 500 to 1000 V. 

With this move it is intended to realize a considerable step of ration- 
alization. 

Meanwhile, further new lighting systems of a comparatively new type of 
protection have been developed for the underground installation. Such sys- 
tems of illumination of intrinsic safety are available for a miximum of six 
small fluorescent tubes of 6 or 8 watts or for 5 such tubes of 15 watts each 
which are operated via a common generator of a small but high frequency 
voltage. Similar systems are applied already in United kingdom and in the 
United States of America; however, they have not been approved in Germany 
because of the different regulations. 

So far this kind of illumination has not been used with success in 
Germany for pure economical reasons. 

A research program welcomed by the German Research Minister is said to 
contribute to making this lighting system economical and mature for mass 
production. 

Another research program is dealing with the development of a new 
"personal miner's" lamp. 

This work of engineering still being in the early stage, I am able of 
talking only about what the Adolf Schuch Company has done so far. 

It is our intention to create a system that has some advantages compared 
with the types which are presently on the market and which comprise a helmet 
and an attachable lighting fixture with Ni-Cd-battery (Figure 11) . 

The miner's lamp known has a few disadvantages which render the minor's 
work more difficult by reducing his freedom of motion. It is fixed to the 
front side of the helmet, thus causing a certain inbalance of the protective 
headwear. According to the result of consultations and investigations, such 
an inbalance may lead to unconscious wrong positions of the head and con- 
sequently to early symptoms of tiring. 



59 





FIGURE 11. - New personal miner's lamp 



60 

The heavy supply cable fixed to the helmet is another object that dis- 
advantageously influences the freedom of motion since in case of certain 
movements it will change the position of the helmet and of the lamp. This 
fact will require an adjustment which means that the work will, of course, 
have to be interrupted. Due to its shape the source of electricity fixed to 
the belt is very troublesome for works to be made in a horizontal or in a 
cowered position as well as for belt runs. 

The greatest disadvantage, however, is that it is very heavy and that as 
a result from its one-sided fixation, it will lead the faulty bearing as well, 
The source of light itself is an extremely bundled point projector thus caus- 
ing too much contrast in the light/dark zone. 

The new system being developed is said to eliminate all such disadvan- 
tages (Figures 12 and 13). 

The new cap lamp; the design of which is based on numerous economical, 
medical, and ergonomical investigations, as well as on those of lighting 
engineering, will offer considerable advantages on the whole. 



61 




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62 



TITLE OF PAPER: UMWA/BCOA/MSHA Mine 
Illumination Survey 

AUTHOR: Mr. Glenn Beckett 

United Mine Workers of America 
Charleston, West Virginia 



Mr. Beckett currently serves as Chief Electrical Inspector for the 
United Mine Workers of America Safety Division International, Bridgeport, 
West Virginia. Prior to his present position, he was employed in the 
coal industry for 21 years as an electrician and mechanic. He worked two 
years as motor mechanic and leader in the General Electric rebuild shop, 
and was a mining and mine maintenance instructor for two years at Boone 
Career Center, Boone County, Danville, West Virginia. 

Mr. Beckett serves on the Joint Industry Health and Safety Committee, 
the CIE TC-4.10 Mine Lighting Committee, the Ad Hoc Subcommittee of the 
IEEE for mine-related subjects, and the Advisory Committee for the VPI 
Annual Institute on Coal Mine Health, Safety and Research. 



63 

UMWA/BCOA/MSHA MINE ILLUMINATION SURVEY 

by 

Glenn Beckett 1 



ABSTRACT 

Regulations requiring the illumination of working places in underground 
coal mines (CFR 30, 75.1719) became effective July 1, 1978. In April 1979, 
ten months had elapsed since the effective date, and a number of complaints 
concerning illumination were being directed to UMWA and BCOA officials. 

With the cooperation of MSHA, a Joint Industry Health and Safety Commit- 
tee was appointed to conduct a survey to solicit comments and suggestions from 
equipment operators and other mine personnel in order to identify any problems 
associated with mine illumination systems. The Committee consisted of one 
UMWA representative, one BCOA representative, and three MSHA representatives. 

Two surveys were conducted — the first represented a cross-section of con- 
tinuous miner and longwall sections in coal seams above 42 inches presently in 
use in the coal industry, and the second continued to cover specific problem 
areas such as low coal (seams below 42 inches) , conventional equipment sec- 
tions, direct-current power supplies, battery-powered scoops, and auger miners 

The committee found that improved lighting in working places is proving 
to be beneficial, and resulting in improvement of the safety of the miners. 
It should result in an increase in efficiency of mining operations. A great 
number of problems remain to be solved, but are not insurmountable. 

Work for improved lighting is continuing by the committee in cooperation 
with USBM to help solve these problems. 

It is the consensus of this committee that "with the cooperation of all 
parties concerned" other problem areas should be surveyed, and that the health 
and safety of all miners can be greatly improved. 

INTRODUCTION 

Regulations requiring the illumination of working places in underground 
coal mines (CFR 30, 75.1919) became effective July 1, 1978. In April, ten 
months had elapsed since the effective date and a number of complaints con- 
cerning illumination were being directed to UMWA and BCOA officials. 

The Joint Industry Health and Safety Committee, with the cooperation of 
MSHA, appointed a committee to conduct a survey to solicit comments and sug- 
gestions from equipment operators and other mine personnel in order to iden- 
tify any problems associated with mine illumination systems. 

Chief Electrical Inspector, United Mine Workers of America, Charleston, WV 



64 

The Committee consisted of one UMWA representative (Glenn Beckett, Chief 
Electrical Inspector), one BCOA representative, (Randolph Slone, Electrical 
Engineer, Eastern Operations Staff, Westmoreland Coal Company), and MSHA rep- 
resentatives (Cecil Lester, Coal Mine Specialist, CMS&H; and Robert Peluso, 
Chief, Special Projects, Technical Support), and Ralph Rhinehart, Chief, 
Beckley Electrical Testing Laboratory. 

The illumination systems included in the first survey represented a 
cross-section of continuous miner and longwall sections in coal seams above 
42 inches presently in use in the coal industry. The second survey continued 
to cover specific problem areas such as low coal (seams below 42 inches) , con- 
ventional equipment sections, direct-current power supplies, battery-powered 
scoops, and auger miners. 

SURVEY METHOD 

The survey consisted of two parts. The first part dealt with observing 
the illumination systems and comparing the system with the approved STE con- 
figuration. The second part was a series of questions that was asked of each 
miner who operates the equipment or works around the illumination system. 

Prior to the Committee arriving at the mine, each company was asked to 
make available to each member of the Committee a copy of the approved STE. In 
most instances, light measurements were made with a Go, No-Go meter during the 
discussions about the STE. 

After the illumination system was compared to the STE, miners were indi- 
vidually asked questions about their experience with the illumination sys- 
tems. A questionnaire was prepared by the UMWA and BCOA representatives to 
guide the questioning part. Some of the questions asked were as follows: 

1. What was your first impression when you saw the lights? 

2. What is your opinion of the lighting system now? 

3. How long did it take for you to get used to the lights? 

4. How long does it take for your eyes to adjust when you leave the 
illuminated area? 

5. How long have you worked around the lights? 

6. Do any of the lights bother you? 

7. Do you have any recommendations for improvements? 

Also, discussions were conducted with mine officials and safety commit- 
teemen of the UMWA, who accompanied the delegation during the mine visit. 
These discussions followed no specific format and only dealt with the general 
experience of installing the illumination systems and miners' acceptance. 






65 

DISCUSSION OF FINDINGS 

During the survey, eighteen (18) continuous miner sections and one (1) 
longwall unit at eleven (11) mines in five (5) states were visited, and the 
seam heights varied from 42 inches to 9 feet. Illumination system installed 
on thirty-six (36) machines (not including shuttle cars and longwall) were 
observed and questions were asked of one hundred and two (102) miners. 

Approximately seven percent (7%) of the miners interviewed wanted the 
illumination systems removed and ninety-three percent (93%) did not want the 
lights removed. Fifteen percent (15%) had no complaints with the systems pro- 
vided and wanted no changes. In general, the majority (78%) of the miners 
interviewed, while expressing a favorable acceptance of the illumination sys- 
tems provided, identified problem areas. 

Problem lights were usually located very close to the work area of the 
miners and the problem areas will be discussed. 

Continuous Miners 

1. Light located on/ in canopy - extreme glare to operator, helper and 
shuttle car operator and an obstruction to operator. 

2. Light located immediately inby operator's position - obstructs opera- 
tor's vision and creates glare for both operator and helper. 

3. Not enough light on face - cannot see cutter head. 

4. Lights located on offside of miner - direct view of operator and 
glare to shuttle car operator. 

5. Light located in floor of operator's deck - obstruction to operator 
and glare to operator and helper. 

Roof Bolting Machines 

1. Light located on drill canopy - glare and insufficient light on hole 
being drilled. 

2. Lights located adjacent to tool trays - extreme glare and obstruction, 

3. Lights located on tramming canopy - extreme glare and obstruction. 

4. Lights located immediately outby tramming deck - glare when tramming. 

5. Lights located on TRS boom - glare. 

Pick-up Loading Machines 
1. Light located behind operator - glare when loading shuttle cars. 



66 

2. Light located on canopy - glare to operator. 

3. Insufficient light in front of loader. 

Shuttle Cars 

1. Insufficient light. 

2. Lights covered up or improperly oriented. 

In many instances the problem lights were either covered or painted. 
When these situations were encountered and other problems were identified and 
lights were not covered, discussions with the miners were directed toward what 
recommendations they had to minimize the problem and many constructive ideas 
were presented by the miners. The miners usually recommended additional 
shielding, additional diffusing, less intensity, or relocating. (Often the 
recommendation was "remove the light"; but when the miners were questioned 
about the benefit of having lights in those areas, most indicated that the 
lights did help them to see better the surroundings of the machine if the 
glare could be minimized. Most miners stated that the lights did improve 
their peripheral vision and they didn't have to spot their cap lamp to see the 
surroundings. 

The continuous miner operators and helpers expressed that the illumina- 
tion provided helped them to see the roof, face, and ribs better. They also 
stated they were better able to observe their trailing cable and other 
personnel in the immediate work area. Roof bolter operators expressed that 
they were better able to see their surroundings, to observe the top and the 
hole being drilled. Shuttle car operators stated the illumination helps them 
to position their car when being loaded and to watch the top better. 

The most positive comments' received on illumination were on the one long- 
wall unit we observed. The miners expressed a very favorable acceptance of 
the illumination provided with only minor complaints concerning the location 
of the fixtures. 

Although, in general, the illumination systems were well received by the 
miners, approximately 85 percent of the illumination systems observed con- 
tained problem areas that generated complaints from the equipment operators or 
helpers. The majority of these complaints were caused by visual impedance 
(discomfort glare, disability glare, veilings, and after images) from light 
sources. Obtaining the required light levels is usually not a problem; 
obtaining it without discomfort glare is a problem. Discomfort glare is a 
difficult problem because it is very subjective. It does not affect all 
individuals to the same extent, and so far it has not been amendable to a 
simple measurement. 

In almost all cases when discomfort glare was encountered, the cause was 
poorly designed and/or installed light fixtures. The light fixtures were 
placed in direct view of the machine operator and/or helper, did not contain 
proper diffusing materials, or shielding techniques were not properly 



67 

utilized. The majority of these problems can be resolved by modification of 
the Statements of Test and Evaluation, utilizing the procedure outlined in the 
Administrator's for Coal Mine Safety and Health memorandum of March 5, 1979. 

In 76 percent of the illumination systems observed, the STE was not being 
totally complied with. Failure to comply with the STE usually dealt with 
location of lights, angle of lights, lights covered or painted, lights very 
dirty, lights not burning, or lights not installed. 

During the survey, mine management and maintenance personnel interviewed 
expressed dissatisfaction with the types of luminaries and installation draw- 
ings provided by the illumination manufacturers. Many stated that the fix- 
tures provided were of "Mickey-Mouse" design and were not "mine duty" and 
lacked adequate mechanical protection and glare suppression. 

The placement of lights on machines is a difficult task because of retro- 
fitting rather than designing the lights as an integral part of the machine. 
While illumination manufacturers provided installation drawings, these draw- 
ings only show general arrangements of the machine and call for exact loca- 
tions for fixtures. When these fixtures are installed according to these 
drawings, many are placed in areas unacceptable to the equipment operator or 
vulnerable to mechanical damage. These personnel also stated that equipment 
manufacturers were not providing equipment with illumination systems ade- 
quately installed as an integral part of the machine. 

From our observations made in mines in coal seams greater than 42-inch 
thickness, the technology exists to provide the required levels of illumina- 
tion in a manner acceptable to most miners; however, there is a definite need 
for improved diff users, better shielding techniques, small low glare lumi- 
naires for critical areas, better system designs, improved installations, and 
increased knowledge of illumination techniques. 

Fourteen (14) sections at eleven (11) mines in three (3) states were 
visited, and the seam heights varied from 26 inches to 42 inches. Illumina- 
tion systems installed on twenty-four (24) machines (not including shuttle 
cars) were observed and questions were asked of fifty-seven (57) miners. 

Approximately sixty- three percent (63%) of the miners interviewed wanted 
the illumination systems removed and thirty-seven percent (37%) did not want 
the lights removed. Ten percent (10%) had no complaints with the systems pro- 
vided and wanted no changes. Twenty-seven percent (27%) expressed a favorable 
acceptance of the overall lighting provided but recommended changes to alle- 
viate problem areas. The number of dissatisfied miners that operate or work 
in proximity to equipment with lighting systems clearly attests to the fact 
that the problems of complying with the illumination regulations in an accept- 
able manner are much more difficult in seams less than 42 inches in thickness. 

Much of the dissatisfaction was generated by glare problems created by 
inadequate light fixtures, improper lighting system design, and poor installa- 
tion and maintenance. Industry personnel display an amazing lack of know- 



68 

ledge regarding lighting technology, available lighting equipment and the 
technical requirements of the regulations. Many responsible personnel stated 
that they had never seen or heard of the Administrator's policy memorandum 
outlining MSHA policy regarding illumination regulations and the procedure for 
modification of Statements of Test and Evaluation. 

In many instances the miners refused to operate the lights long enough to 
become accustomed to them and stated that they only turned the lights on when 
an inspector or supervisor was present. Very few of the systems were 
installed in conformity to the STE, and coal dust and grease were allowed to 
accumulate on many of the light fixtures to the extent that very little light 
was being provided. The committee observed lights not burning, lights 
covered, and areas where the light fixture had been removed. Also, in many 
instances, no effort was made to place the light source out of the machine 
operator's direct vision, forcing the operator to gaze continually into a 
bright light source. Several systems observed were connected in such a manner 
that the lights only burned when the machine pump motor was running. This 
continual changing from dark to light to dark is very annoying and is not 
acceptable to the miners. 

Another important cause of discomfort glare which was responsible for so 
many negative comments from miners is the fact that most of the currently 
available light fixtures are totally unsuitable for use in many of the criti- 
cal areas where light fixtures must be installed in a miner's direct field of 
vision. These fixtures were manufactured with a minimum of optical engi- 
neering and with little regard for the basic techniques of light transmission 
and distribution. Once a light fixture is developed to a barely marketable 
state, very little or no research effort has been devoted to improvement or 
correction of apparent deficiencies. 

Working places are normally driven wider in thin coal seams than in the 
thicker seams. The Committee observed working places with widths as great as 
30 feet during this survey. The widest working places observed during the 
survey of seams above 42 inches were 20 feet. Mining machine frames are 
normally 8 to 9 feet in width regardless of seam height. Therefore, to 
illuminate the rib in this coal seams, the light must be transmitted a greater 
distance horizontally. Since a basic law of physics states that light dimin- 
ishes as the square of the distance, light sources of more than three times 
the intensity are required to illuminate the coal rib in thin coal seams. 
The miner normally works on his hands and knees and the light fixtures of 
necessity are installed at eye level, which compounds the glare problem. 

Another deterrent to the overall effort to provide proper illumination of 
working places is and has been the reluctance of original equipment manufac- 
turers to include facilities for lighting in new equipment design. New 
machines are being delivered to coal mines daily that are not equipped with 
lighting systems, and the mine operator is forced to retrofit the new machine 
and install the required lighting equipment. Often there is absolutely no 
available space for installation of the lighting equipment. This results in 
light fixtures and power supply compartments being installed in the operator's 



69 

compartment and on the side of machines where they are vulnerable to mechani- 
cal damage and can create a hazardous condition to the equipment operator. 

Auger-type continuous mining machines and bottom coal cutting machines 
that are prepelled by wire ropes present special illumination problems. It is 
necessary to set metal jack pipes near the face for anchoring the wire ropes 
that are used to propel these machines. Light fixtures installed on these 
machines shine directly into the face of jacksetters and machine helpers while 
they are setting these jacks. Also, jacksetters and machine helpers signal to 
the machine operator by means of their cap lamps when it is necessary to 
tighten or release the ropes during routine operation of the machine. All the 
illumination systems developed to date for these machines have interferred 
with the miner's ability to signal to each other. Also, the jacksetters crawl 
around the machine with light fixtures installed at eye level and glare is 
created. Several fatal accidents have occurred on these machines when jack- 
setters are caught in the rotating bits on these machines; therefore, in such 
a dangerous situation, even a small amount of glare is not acceptable. 

RECOMMENDATIONS 

If the expected benefits in safety, health, and efficiency are ever real- 
ized from the illumination effort, the joint cooperation of labor, industry, 
and government is absolutely essential. The majority of miners' complaints 
regarding illumination of working places can be resolved by industry, labor, 
MSHA, and equipment manufacturers and suppliers adherence to the following 
recommendations . 

Industry 

1. Do not install lights inside operator's positions, under canopies, 
or other locations that interfere with entrance to or exit from the 
operator's deck. 

2. Whenever practical, locate or shield light sources so that they are 
not in the machine operator's direct field of vision. Where it is 
necessary to place light sources in a miner's field of vision, 
proper diffusing or guarding should be used to reduce discomfort 
glare to an acceptable level. Never place bare, undif fused light 
sources, except headlights operating in the direction of travel, 
(i.e., headlights on continuous miners, loading machines, scoops, 
etc.) in the direct view of miners. 

3. Whenever practicable, install lighting systems in accordance with 
the STE. When a light fixture installed in accordance with the STE 
created glare or other visibility problems for miners, obstructs 
entrance to or exit from operators' compartments, or creates main- 
tenance problems, place the light fixture in the optimum location 
and request modification of the STE in accordance with the Adminis- 
trator's for Coal Mine Safety and Health memorandum of August 2, 
1979. Future installation of lighting systems on similar equipment 



70 



operating under similar mining conditions should be made in accord- 
ance with the modified STE. 

4. Maintain light fixtures free from accumulations of coal dust, dirt 
or other contaminants and in safe operating condition. 

5. Do not wire lighting systems into the machine electric circuitry in 
such manner that will cause the lights to go on and off as the 
hydraulic pump motor is started and stopped. The lights should burn 
at all times the machine is energized in the working place. 

6. Listen objectively to miners' complaints. Correct those complaints 
in accordance with the above recommendations and then insist that 
the light be left on at all times the machine is energized in the 
working place. 

7. Prior to purchasing lighting equipment, industry officials should 
carefully evaluate available hardware and purchase lighting equip- 
ment that is suitable for the mining conditions found in each mine. 
There are lighting systems being marketed that are practically 
impossible to maintain and are unsuitable for use in certain mining 
conditions and unacceptable to miners. 

8. The interior of cabs and canopies, except control levers and 
switches, should be painted with flat black paint to minimize 
reflected glare. Guards over lens should also be painted with flat 
black paint. 

Labor 

1. Keep lights clean on your machine. 

2. Report promptly any lights not burning. 

3. If a particular light blocks your vision or creates discomfort 
glare, do not paint the lens or cover the light fixture, which 
destroys the permissibility of the machine, but report it to your 
supervisor and request corrective action. 

4. Keep lights turned on at all times the machine is energized in the 
working place. 

5. Feel free to make any recommendations for improvement of lighting 
systems to industry officials, labor officials, or MSHA officials. 
Every recommendation shall receive prompt consideration. 

MSHA 

1. Heatlights on continuous mining machines and loading machines should 
be oriented so that the maximum amount of light is provided on the 



71 

coal face. This improves the contrast ratio and improves the abil- 
ity of the machine operator to see the location of the cutting bits 
or gathering arms. Therefore, to allow the most efficient utiliza- 
tion of the available light, light measurements should not be taken 
of the floor area between the cutter boom hinge pin or gathering 
head hinge pin and the coal face. 

2. Light fixtures installed adjacent to supply trays on dual-head roof 
bolting machines create objectionable glare to the operator and 
helper. Therefore, to allow removal or repositioning of these light 
fixtures, the lighting system should be considered to be in compli- 
ance if the required level of light is provided as determined by 
illumination measurements made with the drill heads either together 
or separated approximately 8 feet and in position to drill holes or 
install roof bolts. 

3. In coal seams under 42 inches in thickness, hazards to miners from 
falls of rib or face or stumbling hazards are practically nonexist- 
ant. In thin seams, the glare problem is much worse than in thicker 
seams. One obvious method of decreasing discomfort glare is to 
reduce light intensity. Experience with roof bolting machines has 
shown that illumination of the area 5 feet in all directions from 
the machine is adequate in thin coal seams. This is supported by 
the fact that a greater percentage of roof bolting machine operators 
and helpers found the lights to be acceptable and made positive com- 
ments. Therefore, the area to be illuminated for continuous miners, 
coal drills, cutting machines, and loading machines should be 
changed to include an area of 5 feet from each side of the machine. 
This change would allow additional diffusers to be installed on 
existing light fixtures to reduce the glare. 

4. In coal seams less than 42 inches in thickness, the area required to 
be illuminated by remotely controlled continuous miners should be 
changed to exclude the area of the right side of the working place 
extending a distance of the outby one half of the main frame shown 
in Appendix V until glare-free light fixtures are made available. 

5. In coal seams less than 42 inches in thickness, measurements should 
not be taken of the area in front of and to the side of the roof 
bolting machine operator until glare-free light fixtures are devel- 
oped suitable for lighting this critical area. 

6. In all coal seams, regardless of height, all scoops being used as 
load-haul-dump vehicles, clean-up scoops, or supply vehicles should 
be illuminated in accordance with Section 75. 1719-1 (e) (6) while 
such vehicles are being operated in the working place. Furthermore, 
to provide for the maximum utilization of the available light, when 
the height of the coal does not permit installation of light fix- 
tures on top of these vehicles, the areas required to be illuminated 
the same as higher coal. 



72 



Tests conducted by the UMWA/BCOA/MSHA illumination committee in the 
No. 1 Mine, Coal X, Incorporated, Christian, Logan County, West 
Virginia, have shown conclusively that load-haul-dump vehicles and 
other battery-powered scoops illuminated either in compliance with 
Section 75.1719-l(e) (6) or the same as shuttle cars. 

7. Because of the hazards created by current lighting systems, the 
illumination standards should not be enforced for a rope-propelled, 
auger-type continuous miners and bottom cutting machines for a 
period of 12 months to allow the Bureau of Mines time to conduct 
research toward developing a safe, glare-free system acceptable to 
miners. 

8. Sufficient research funds should be made available by the Bureau of 
Mines for the rapid development of glare-free light fixtures for 
critical areas. There is a definite need for an immediate crash 
research program to develop low-glare light fixtures for these crit- 
ical areas. 

9. Federal mine inspectors should insist that light fixtures be 
installed and maintained in accordance with the STE; however, when 
the inspector observes a lighting system that is not installed in 
compliance with the STE, the inspector should explain the STE modi- 
fication procedure to the mine operator and offer MSHA assistance in 
modifying the STE. 

10. A meeting of light fixture manufacturers and mining equipment manu- 
facturers should be held in the near future for the purpose of 
allowing the committee an opportunity to discuss their findings dur- 
ing the survey and the deficiencies in current design of lighting 
systems. 

11. A series of seminars for the distribution of information regarding 
available illumination technology and equipment should be held at 
strategic locations in the various coal-producing regions. Chief 
electricians, electrical engineers, maintenance foremen, electri- 
cians, mechanics, and other industry personnel directly involved in 
installation and maintenance of lighting hardware should be invited 
and encouraged to attend. 

12. Technical Support should require more stringent glare controls in 
critical areas when considering applications for Statements of Test 
and Evaluation. 

13. MSHA should explore methods for prohibiting delivery of new, used, 
or rebuilt electric face equipment to coal mines unless means for 
compliance with Section 75.1719 is provided. 

14. MSHA district managers should forward a copy of all modifications of 
Statements of Test and Evaluation to the lighting equipment manu- 



73 

facturer so that these changes may be incorporated into future 
lighting system design. 

Equipment Manufacturers and Suppliers 

1. Manufacturers and used equipment dealers should not ship machines to 
coal mines unless provisions are made for compliance with the illu- 
mination regulations. Design of new machines and rebuilding of 
existing machines should include provisions for installation of 
light fixtures in recessed areas or other protected locations. 

2. Persons designing lighting systems should concentrate their efforts 
on making systems more glare free. 

3. The interiors of cabs and canopies of new and rebuilt equipment, 
except control levers and switches, should be painted with flat 
black paint to minimize discomfort glare. Guards over light lens 
should also be painted with flat black paint. 

4. The services of qualified physicists, optical experts, and illumina- 
tion engineers should be obtained and used in the design of light 
fixtures. 

The committee has found that improved lighting in working places is prov- 
ing to be beneficial and resulting in improvement of the safety of the miners 
and should result in an increase in efficiency of mining operations. A great 
number of problems remain to be solved but are not insurmountable. 

Work for improved lighting is continuing by the committee in cooperation 
with USBM to help solve these problems. 

It is the consensus of this committee that "with the cooperation of all 
parties concerned" other problem areas should be surveyed, and that the health 
and safety of all miners can be greatly improved. 



74 



TITLE OF PAPER: Overview of U.S. Bureau of Mines 
Illumination Research Program 

AUTHOR: Mr. William H. Lewis 
U.S. Bureau of Mines 
Pittsburgh Mining Research Center 
Pittsburgh, Pennsylvania 



Mr. Lewis has been employed at the USBM Pittsburgh Research Center 
since 1978, and is presently Supervisory Engineer of the Bureau's Mine 
Illumination Research program. 

Mr. Lewis is a graduate of the University of Pittsburgh, and holds 
a B.S. Degree in Electrical Engineering and a Masters Degree in Education. 

He has held a number of technical and management positions in private 
industry involving product development in areas of laboratory instrumenta- 
tion and consumer products. Prior to joining the Bureau, he held the 
position of Director of Engineering at Radioear Corporation. 

Mr. Lewis is a member of the American TC-4.10 Committee 



75 



OVERVIEW OF THE U.S. BUREAU OF MINES ILLUMINATION RESEARCH PROGRAM, 1981 

by 
William H. Lewis 



ABSTRACT 

Since the passage of the Coal Mine Health and Safety Acts of 1969 and 
1977, the U.S. Bureau of Mines has undertaken a major research effort in the 
area of mine lighting. This paper will attempt to give an overview of the 
research efforts to date, its present state and anticipated future efforts in 
the following three major areas: 

Underground Coal Mine Illumination 

Surface Mine Illumination 

Underground Metal and Nonmetal Mine Illumination 

INTRODUCTION 

"the eye has always been held the choicest gift of nature - the most 
marvelous product of her plastic force ... dwell on its penetrating power, 
on the swiftness of succession of its brilliant pictures, and on the riches 
it spreads before our sense" 

Helmholtz 

Why Mine Lighting ? 

Depending on the audience, one could answer the question with a question 
as Socrates might have done. Why do we light our factories , our schools , our 
hospitals , our homes , our streets ? The need for light in our environment is 
obvious. Of all of our senses, vision is the most remarkable and informative. 
It is estimated that 80 percent of all human knowledge has been acquired 
through man's sense of vision and is our primary source of sensually perceived 
data and environmental awareness . 

What Are the Benefits ? 

If man's primary sense (vision) is impaired for whatever reason, either 
by disfunction of the eye itself or by a lack of adequate illumination, man 
cannot function to his fullest potential. The benefits of enhancing this 



^roup Supervisor, Mine Illumination Research, U.S. Bureau of Mines, 
Pittsburgh Research Center, Pittsburgh, Pennsylvania 



76 



sense are self-evident, increased safety and productivity . In the words of 
Roger Bacon, "He that cannot see well, let him go softly. What the eye has 
seen, the hand may do." 

Safety professionals recognize that adequate illumination is essential 
to a safe and productive work environment in industrial settings. The need 
for adequate illumination in underground coal mines is even greater. Congress 
recognized this essential need in the Coal Mine Health and Safety Acts of 1969 
and 1977 and charged the Secretary of the Interior with the responsibility and 
the authority for developing and prescribing minimum illumination standards 
for mining environments. Since the passage of the "Acts," the Bureau of Mines 
has undertaken a major research effort to bring better lighting systems and 
technology to the mining industry. 



is 



Today, 85 percent of all required underground coal mining machinery 
equipped with an approved lighting system and represents one of the most 
evolutionary changes to the mining environment in the last decade. 

PROGRAM STRUCTURE AND OBJECTIVES 

The present mine illumination research program is divided into three 
major areas: 

. Underground Coal Mine Illumination Research 

. Surface Mine Illumination Research 

. Underground Metal and Nonmetal Mine Illumination Research 

The primary objective of the program is to reduce accidents and injuries 
and improve safety in the working environment of miners through the use of 
improved lighting technology. 

Recent emphasis of the program focuses on six major efforts: 

. Illumination System Hardware Development 

. Basic Studies 

. Demonstration of Underground Coal Mine Illumination Systems 

. Factory Integration of Illumination Systems into Mining Machinery 

. Feasibility Studies of the Proposed Surface Mine Illumination 

Standards 
. Illumination Standards Development for Underground Metal and Nonmetal 

Mines 

ILLUMINATION SYSTEM HARDWARE DEVELOPMENT 

This program is an on-going effort involving the development of new and 
improved lighting systems and related equipment for use in mining environ- 
ments. Present efforts focus on the development of (1) an improved miner's 
caplamp and battery and (2) low glare machine mounted lighting systems for 
thin seam coal mine applications. 



77 



Miners Caplamp Development 

The present day miner's caplamp and battery system has for many years 
proven to be a highly reliable and indispensable aid to miners and has under- 
gone few changes in its many years of existence. Recent developments in 
battery technology, however, have made additional improvements possible. Over 
the past two years, Energy Research Corporation, under contract to the Bureau 
of Mines, has been developing a new caplamp battery. The new battery (Fig. 1) 
is based on nickel cadmium technology and features significant reductions in 
weight and size as compared to the conventional lead acid battery. Among the 
more significant improvements are a 48 percent reduction in weight and a 15 
percent reduction in volume. Cycle life has also been increased and is 
expected to be in the range of 1000 charging cycles as compared to 400 for the 
lead acid battery. The battery has been designed to be compatible with exist- 
ing charging systems and caplamps, which illuminates the need to replace this 
equipment when phasing in the new batteries. 




FIGURE 1. - Prototype nickel cadmium battery (right). 
Conventional lead acid battery (left) . 



78 



TABLE 1. - Comparative Battery Specification 



Specification 


Nickel Cadmium 


Lead Acid 




2.42 
3.5 
15.0 
52.0 
21.4 
46.1 
1000 
$50 


4.66 
3.7 




12.0 
44.0 


Cost (20,000 u/yr) 


9.5 
53.4 
400 
$30 



To enhance the overall marketability of the new caplamp system, addi- 
tional features (Fig. 2) are being incorporated into the design. A new 
reflector has been designed to accept the tungsten halogen type bulb shown in 
Fig. 3. The new bulb will offer the equivalent light output of the conven- 
tional incandescent bulb, but with reduced power consumption and greater life 
expectancy. Because the new bulb has only one filament, two bulbs will be 
used as a failsafe feature. The headpiece assembly will be similar to the 
present design, except that an elevation adjustment will be provided to allow 
the miner some directional control of the light beam. This should be partic- 
ularly useful in very low seam coal mines where the miners do considerable 
crawling. In a crawling posture, the miner's head is pointed somewhat down- 
ward and consequently the light beam does not project very far in front of 



Duo I Tungsten 
Halogen Lamps 



Elevation 
Adjust 



FIGURE 2, 



Illustration of a prototype 
caplamp system and features 



Segmented Cord 
•Coiled Ends 
•Straight Center 
Sect i on 



Cord Disconnect 
Mechanism 




Lightweight 
Nickel Cadmiu m 
Battery 



79 




FIGURE 3. - Tungsten halogen lamp (right). 

Conventional incandescent lamp (left) 



him. With the elevation adjustment, the miner can adjust the beam to project 
farther in front without repositioning his head to an uncomfortable position. 
Other features being considered are a coiled battery cord and a cord- 
disconnect mechanism. Human factor studies of battery cord designs suggest 
that a coiled cord may provide greater safety. The presently supplied cap- 
lamp cord comes in one standard length, which when worn by shorter miners has 
a tendency to bow out away from the body (Fig. 4). In comparison, the coiled 
cord design is more adaptable to variations in body dimensions and has a 
tendency to lay closer to the body, which reduces the probability of the cord 
being snagged or caught in a piece of rotating machinery. Consideration is 
also being given to a device which would allow a snagged cord to disengage 
from the battery at some predetermined level of tension. Such a device could 
prevent the miner from being pulled into a piece of machinery in the event 
the cord became entangled. Although preliminary studies suggest these 
features are beneficial, cost considerations and field studies will ultimately 
determine whether they will be incorporated into the final product. 






80 





FIGURE 4. - Body conformity of coiled cord configuration (left). 
Standard cord (right). 



Low Glare Illumination Systems 

Conceptually, the notion of providing illumination in underground coal 
mines appears simple, but in practice, its implementation is filled with 
subtle and complex problems. A recent survey* conducted by the UMWA/BCOA 
Joint Industry Health and Safety Committee reported on problems and worker 
complaints of illumination systems installed in underground coal mines. Most 
of the complaints related to the problem of vision impedance (discomfort 
glare, disability glare, veiling reflections and after images) caused by the 
light sources. To address this problem, the Bureau has undertaken a number of 
projects to develop low glare illumination systems, particularly for use in 
thin seam coal mine applications where glare problems are more prevalent. 

Recent efforts in this area have led to the development of the first of a 
series of prototype low glare illumination systems (Fig. 5). The new 
fluorescent lighting system is small in size and can be mounted vertically 
with as little as 13 inches of vertical mounting space. The luminaires 1 small 
size and vertical mounting capability allow the lighting designer to make 



81 




FIGURE 5. - Prototype low glare lighting system (left) 
Dif fuser/guard removed (right). 



better use of the light distribution pattern of cylindrically shaped fixtures. 
The fixture has been designed to accommodate a number of lamp modules which 
can house 1, 2, or 3 fluorescent lamps and gives the lighting designer some 
flexibility in selecting the light output. Each lamp module which contains 
its own reflector can easily be interchanged in the fixture. The lightweight 
compact fixture measures only 12-1/2 x 3 x 4 inches. Power is supplied 
through a 90 degree packing gland which conserves vertical mounting space. 
The experimental packing gland has been designed for "quick disconnect" to 
facilitate maintenance and fixture replacement. To reduce glare, the fixture 
has a unique snap on white translucent plastic diffuser which acts as a guard 
and reduces the source brightness by spreading the light over a larger sur- 
face area. The dif fuser/guard can be readily removed for cleaning, or 
replaced without tools, and does not affect the explosion proof integrity of 
the fixture. Prototype systems are being designed to function from both 



82 



alternating and direct current supplies. The direct current system will 
function directly from a 300 VDC power source without an inverter ballast. 

Another recently initiated program is investigating more novel fixture 
designs with emphasis on glare reduction. One system utilizes a small pre- 
focused tungsten halogen lamp similar to the ones commonly used in slide pro- 
jectors. The small but rugged incandescent lamps offer relatively good 
operating life and low cost; making them ideally suited for mining applica- 
tions. The light output of the lamp is a highly focused intense beam of 
light, and as such is not suited for area lighting applications, but when 
fitted with a novel diffuser assembly being explored; the prospects look 
promising. The diffusion technique involves projecting the intense beam 
of light onto a curved matt white surface which acts as a diffuser and 
secondary source; the main source (lamp) being kept out of the field of 
view of the worker. 

Concepts using fibre optics to pipe light from a main source or sources 
to various locations around a machine are also being explored. The narrow 
beam of light transmitted through the fibre optic cables would then be termi- 
nated at desired locations with diffuser assemblies similar to the ones 
described above. This technique offers several advantages over present 
lighting systems in both safety and cost; in that fewer explosion proof 
enclosures would be required and fewer elecrical cables would be routed 
around the machine. The diffuser assemblies which terminate the fibre 
optics cables need not be explosion proof and can be made more inexpensively. 

Packaging concepts for fluorescent lamps are also being investigated 
that have a very low profile and rectangular in shape. The design will use 
several fluorescent lamps of low wattage and brightness and will take advan- 
tage of the larger surface area- of the rectangular shape to diffuse the 
light more effectively. These luminaires are contemplated to have application 
on longwalls as well as conventional and continuous mining machinery. 



TO POWER SUPPLY 

(7 

X P LAMP ENCLOSURE 

/ 



(4) DIFFUSE* ASSEMBLIES 



83 




t 



J* 




4 PREFOCUSED TUNGSTEN 
HALOGEN LAMPS 






FIGURE 6, 



REFLECTOR 



(4) FIBER OPTICS 
BUNDLES 



- Illustration of multiple source (incandescent) fiber optics 
lighting concept. 



HIGH PRESSURE SODIUM LAMP 




X/P LAMP ENCLOSURE 



LIGHT PIPES 
IFFUSER ASSEMBLIES 



FIGURE 7. - Illustration of single source (high pressure sodium) for fiber 
optics concept. 



84 



(1) FIBER OPTICS SYSTEM 




FLUORESCENT LAMPS 



X/P INCANDESCENT SOURCE ENCLOS 



URE^ 



FIGURE 8. - Illustration of fiber optics, incandescent and fluorescent 
lighting diffuser assemblies. 



85 



BASIC STUDIES 



This major area in the illumination research program is oriented towards 
researching and solving problems of a more fundamental nature and includes 
programs to develop an underground coal mine illumination handbook; psycho- 
physical studies of glare in illuminated underground coal mines, and the 
development of guidelines for installation and maintenance of underground 
coal mine illumination systems. 

Mine Lighting Handbook 

Findings of the UMWA/BCOA Joint Industry Health and Safety Committee 
Survey of underground coal mine illumination reported that "industry person- 
nel display an amazing lack of knowledge regarding lighting technology, 
available lighting equipment and the technical requirements of the regula- 
tions." In response to the recommendations of the committee, the Bureau has 
undertaken the development of a mine illumination handbook. The objective of 
this program is to provide the mining industry with a comprehensive, authori- 
tative reference text on the subject of underground coal mine illumination. 
The major topics to be discussed in the text will be: 

. Overview of the history of mine illumination and the development of 

federal lighting regulations 
. Lighting fundamentals and optical principals 
. Illumination regulations for underground coal mines 
. Light sources and powering requirements 
. Permissible fixture and enclosure design 
. Light measuring theory and instrumentation 
. Guidelines for installation and maintenance of mine illumination 

systems 
. Design of machine mounted lighting systems 
. Glare control and diffusing techniques 
. Review of available hardware 
. Photography in underground coal mines and permissiblity 

considerations 

The format and style of the text will be written to accommodate readers 
with varying degrees of expertise and educational level and should be a 
valuable reference text for mine maintenance personnel as well as lighting 
engineers and equipment manufacturers. 

Development of Maintenance Guidelines 

The next program in this area was a study to determine the state of the 
art of mine illumination hardware, define lighting system installation and 
maintenance problems and assess personnel acceptance of lighting in under- 
ground coal mines. Longwall as well as mobile face machine illumination 
systems were addressed. The study included a survey of 60 mines, 11 light- 
ing hardware manufacturers and 9 mobile face equipment manufacturers. Major 



86 



problems that were identified in room and pillar installations include damage 
of exposed components, electrical failures and reduced lamp life with extreme 
variability among mining operations. Most longwall lighting installations 
had low to moderate maintenance requirements. Cable damage was found to be 
the most significant problem. Most mobile face equipment operators surveyed 
were in favor of the lighting systems on their machines, but many of them 
complained about glare problems. In contrast, longwall lighting systems were 
unanimously accepted by face personnel and the few complaints received about 
these systems were minor. Based on the survey, general installation and 
maintenance guidelines have been developed and should provide valuable 
assistance to lighting maintenance personnel in reducing maintenance costs 
and machine downtime associated with lighting system failures. A more de- 
tailed discussion of this Bureau program is discussed in a separate paper 
presented at these proceedings . 

Glare Studies 

Another program in this area is a study of glare problems in illuminated 
coal mine environments. This program is an outgrowth of recommendations of 
the UMWA/BCOA Joint Industry Health and Safety Committee survey. Studies to 
date have focused on determining the average glare tolerance of a representa- 
tive sample of miners and a comparison of these tolerance levels with the 
levels of glare that the miners are typically experiencing from their machine 
illumination systems. Standard vision and discomfort glare tests have been 
performed on approximately 170 miners. In-mine data relating to discomfort 
and disability glare has also been taken on a number of different illuminated 
machines with a variety of different lighting systems. Results of this study 
have not been finalized at this time, but a detailed discussion of the test 
methodology and work accomplished to date is presented in separate papers by 
Messiers Guth and Crouch 3 in these proceedings. The ultimate goal of this 
program is to provide a better understanding of the nature of glare problems 
in illuminated underground coal mine environments so that lighting system 
designers and manufacturers are better able to supply the mining industry 
with more acceptable and effective low glare lighting systems. 

DEMONSTRATIONS OF UNDERGROUND COAL MINE ILLUMINATION SYSTEMS 

Over the past several years, the Bureau of Mines has undertaken a pro- 
gram through contract research to assist the mining industry in complying 
with Federal Underground Coal Mine Regulations. Basically, the program has 
provided the expertise for designing, installing, and evaluating illumination 
systems in those areas which pose difficult or unique problems to the mining 
industry in implementing the regulations. Demonstrations have been completed 
on a large number of machine types and work areas including low and high seam 
longwalls, shortwalls, slope operations, and most conventional and continuous 
mining equipment. 



87 



The latest study that has been completed involved lighting system designs 
for 9 machines in four different mining locations. A list of machine types 
and pertinent information is given in Table 2. The overall objectives of this 
program were to: 

. Determine the feasibility of illuminating low seam equipment 

. Determine the reliability of 300 and 600 VDC illumination systems 

. Minimize glare 

. Stress mine worthy design 

. Identify problems for future research 

Results of the program have shown that with good engineering design, 
reliable mine worthy AC or DC illumination systems can be installed in a wide 
variety of seam conditions. In general, the systems were well received by 
the operators, but some complaints were made about glare and. the loss of cap- 
lamp signaling ability. Mineworthy lighting designs were achievable, but a 
high degree of design effort and usually extensive machine modification is 
required. Material costs for the 9 machines varied from $2,222 to $5,550 
with labor costs ranging from $2,500 to $9,375. The overall average cost per 
machine was $8,406 with a range of from $4,722 to $13,852. 




FIGURE 9. - Low seam Joy 14BU10 loader with installed lighting system. 



88 



TABLE 2. - Demonstrated Machines 



Machine 
Height 
Machine Type (in) 


Seam 
Height (in) 

28 to 42 


Lighting System 

(4) Ocenco 

Fluorescent 

(2) Ocenco 

Headlamps 


Electrical 

System 


Joy 1ABU10 24 

Loader 


300VDC 


Joy 12RB 24 

Cutting Machine 


28 to 42 


(6) Ocenco 

Fluorescent 

(4) Ocenco 

Headlamps 


300VDC 


Gallis 4100 24 

Face Drill 


23 to 42 


(5) Ocenco 

Fluorescent 

(2) Ocenco 
Headlamps 


300VDC 


Long Airdox 24 


28 to 42 


(3) Ocenco 

Fluorescent 

(1) Control Products 
Mercury Vapor 


300VDC 


Roof Bolter 




N.M.S. Marietta 48 

Continuous Miner 


96 


(3) Control Products 
Incandescent 
Headlamps 

(4) Control Products 
Fluorescent 


550VDC 


F.M.C. 320A 60 

Roof Bolter 


96 


(8) Control Products 
Fluorescent 


330VDC 


F.M.C. 320H 96 


144 


(12) McJunkin 

Fluorescent 


440VAC 


Roof Bolter 




Continuous Miner 


90 


(3) Ocenco 
Headlamps 

(5) Ocenco 

Fluorescent 


550VDC 


Jov 14BU10 48 


90 


(7) Ocenco 

Fluorescent 


550VDC 


Loader 





89 

FACTORY INTEGRATION OF ILLUMINATION SYSTEMS INTO MINING MACHINERY 

Efforts in this area are directed towards stimulating mining equipment 
manufacturers to integrate illumination systems into their equipment at the 
factory. The objective of the program is twofold: (1) to relieve the mining 
companies from the burden of designing and retrofitting machine mounted 
illumination systems in the field and (2) provide better protection of the 
illumination systems from damage due to roof falls, collisions and in general 
to improve the overall reliability and structural integrity of the systems 
being supplied. To this end, the Bureau has undertaken numerous cooperative 
programs with mining equipment manufacturers; they include such companies as 
FMC Corp., J. H. Fletcher & Co., Long-Airdox Co., National Mine Service Co., 
and Fairchild Inc. 

Although considerable success has been achieved in stimulating equipment 
manufacturers to supply factory equipped illumination systems on their 
machinery; the major objective of achieving truly integrated lighting systems 
has not been accomplished. A recent study performed under Bureau contract to 
assess the state of the art of factory supplied lighting systems reported 
that; all manufacturers of low seam roof bolters and continuous miners can 
currently supply MSHA approved lighting systems. Most of the manufacturers 
install lighting systems that have been designed by lighting suppliers. 
Equipment manufacturers are not supplying approved lighting systems on rope 
propelled bottom cutters or auger type continuous miners because of insuf- 
ficient technology and the lack of adequate low glare illumination systems. 
The three main manufacturers of rope propelled bottom cutters are not 
actively developing lighting systems for this equipment, primarily because of 
a declining demand for their equipment and that higher priority projects are 
consuming the efforts of their relatively small engineering staffs. The 
sophistication of the equipment being supplied varies considerably from one 
manufacturer to another. Most equipment manufacturers are not interested in 
"Factory Integrated Lighting." They feel that the lighting systems would not 
be cost competitive when compared to "Factory Retrofit Systems." A truly 
integrated lighting system usually requires extensive redesign of the machine 
and represents a considerable investment in cost and engineering effort. 
Many of the equipment operators feel that factory integrated systems are not 
feasible because mine operators request particular types or brands of light- 
ing systems which makes it difficult if not impossible to standardize their 
design. Others argue that integrating or recessing the lights into the 
machine superstructure necessitates more lights in the design because some 
peripheral lighting is lost from each of the luminaires when it is recessed. 
Development and tooling costs for new machines are expensive, which means 
standardized lighting designs are a "must." This is not always possible be- 
cause of customer preferences for particular types or brands of lighting 
equipment. Some equipment manufacturers are concerned about future regula- 
tory changes which would obsolete new and expensive equipment designs. Also, 
modifications of the equipment must be approved by regulatory agencies which 
usually involves long periods of time for approval and consequently long 
delays in introducing the equipment to the marketplace. In summary, factory 



90 



integrated lighting system design has not received widespread priority among 
equipment manufacturers, but considerable success has been achieved in stimu- 
lating manufacturers to supply some form of approved lighting system on their 
machines from the factory. 







FIGURE 10. - "Factory Integrated" lighting system on a Fletcher DDM-13 diesel 
powered roof bolter.. 



FEASIBILITY STUDIES OF THE PROPOSED SURFACE COAL MINE 
ILLUMINATION STANDARDS' 



Surface mines in the past were primarily small operations and usually 
carried on during daylight hours, with little or no need for artificial 
lighting. But as stripping operations grew in size, more and more companies 
shifted to around-the-clock operations. With the advent of larger and more 
costly equipment being operated during non daylight hours, artificial light- 
ing became a necessity. Initially, most lighting installed on stripping 
equipment was primarily for task purposes, with very little emphasis placed 
on safety lighting. As the frequency of accidents increased, the need for 
additional efforts in accident prevention became apparent. In the meantime, 
the Mine Safety and Health Administration (MSHA) began work on developing 
minimum lighting standards for surface coal mines and surface work areas of 
underground coal mines, and consequently published proposed mandatory 
standards. 



91 

Safety Lighting for Draglines and Power Shovels 

In cooperation with MSHA and the mining industry, the Bureau of Mines 
has undertaken a number of programs to demonstrate the feasibility of the pro- 
posed surface mine illumination standards. Recent studies have focused on 
the design, installation and evaluation of lighting systems for draglines and 
power shovels. One study has been completed and a second study is nearing 
completion. Safety lighting systems for five draglines and one power shovel 
have been designed and evaluated. The first study involving three medium 
size draglines (Marion 184M, 12-cu-yd, Page 7-32, 20-cu-yd, Marion 7800, 
28-cu-yd) has been completed by Phoenix Products Co. under contract to the 
Bureau of Mines. A more detailed discussion of this project is reported on 
in a separate paper of these proceedings . The second study was contracted 
to Mine Safety Appliances Co . and is nearing completion. This study is also 
reported on in a separate paper and involves lighting systems for two large 
draglines (Bucyrus-Erie 1450, 60-cu-yd , Bucyrus-Erie, 176-cu-yd) and one 
power shovel (Marion 5900, 105-cu-yd) . An outgrowth of the second study has 
been a re-evaluation of the proposed lighting standards relating to the walk- 
ways, ladders and gantries that exist on dragline main frames and booms. 
Currently, these areas are required by the proposed standards to be illumi- 
nated to 5.0 foot candles. As the lighting designs for these areas 
progressed, it became apparent that the amount of lighting required to meet 
the proposed standards would be extensive and costly, and consequently a 
follow-up study was undertaken to investigate the frequency and nature of use 
of these areas and walkways. The findings of the study showed that most of 
the walkways and work areas were used rather infrequently and only for 
maintenance and repair purposes. It was also found that when travel in these 
areas was necessary, it was usually performed during daylight and the machine 
was shut down. Some companies have argued that the lighting would have a 
detrimental effect on safety, because maintenance of the 50 to 100 luminaires 
and associated cabling needed to light these areas would increase the 
frequency of usage of the areas, and consequently increase the workers expo- 
sure to a hazardous environment. Others have argued that the extensive net- 
work of power wiring to the lights may expose the worker to increased 
electrical hazards, particularly when you consider the harsh environment that 
the wiring and fixtures would be exposed to (high vibration, shock, weather 
extremes). A report of these findings has been sent to MSHA officials for 
review. A possible solution to the problem would be to require that travel 
in these areas be performed only when the machine is shut down and during 
daylight hours, and if maintenance or repairs are necessary during nighttime, 
the worker should be required to carry portable lighting. 

Operator response to the new lighting systems has been excellent with 
some reporting increased gains in productivity as well as safety. These re- 
ports suggest that presently supplied task lighting may be inadequate and 
that the additional safety lighting is providing increased visibility for 
production tasks. 



92 





FIGURE 11. - 



Marion 5900, 105 cubic 
yard power shovel. 




FIGURE 12. - Extensive network of walkways 
on board large draglines and 
power shovels. 



93 

ILLUMINATION STANDARDS DEVELOPMENT FOR UNDERGROUND METAL 

AND NONMETAL MINES 

Until recently, the major emphasis of the Bureau's illumination research 
program has focused on developing illumination standards and technology for 
underground coal mines and surface mining operations. In the future, as re- 
search problems are resolved in these areas; increased emphasis will be 
placed on the lighting needs of the underground non coal mining industry. 

The underground non coal mining industry presents a unique mixture of 
diverse mining methods and environments which will require firm definition 
before illumination standards can be effectively developed. To this end, a 
first of a series of fundamental studies has recently been completed. Efforts 
of this program were directed towards quantifying and defining the large 
variety of mining operations, work tasks and work areas associated with under- 
ground non coal mines. Major work locations, activities, and equipment used 
in these locations have been described in detail. In addition, accident 
records have been analyzed and categorized according to work areas and tasks. 

Follow-up studies are now underway to determine the minimum luminance 
requirements for these work areas and tasks. Present work involves the con- 
struction of a simulated mine laboratory where the various tasks can be 
analyzed in a controlled manner. The study will focus on answering basic 
questions, such as, what does the worker have to see to perform his task 
safely and how much light is needed to see? Work is also underway in develop- 
ing a method for collecting in-mine reflectivity data. Since a large amount 
of reflectivity data is required to adequately describe the wide variety of 
work environments, a simple and expedious method for collection is essential. 
Research to date, has developed such a method. Briefly the method will use a 
photographic technique to capture the reflectivity data on film and will in- 
volve taking a picture of a scene or area of interest using standard black 
and white film and a camera equipped with a flash unit. Prior to taking the 
picture, a standardized gray scale card (Fig. 13) is placed in the scene. 
The picture is then taken and the exposed negative is developed and analyzed 
with an optical densiometer. By analyses of the optical density of the nega- 
tive, reflectance values can be determined by comparing the optical density 
of the gray scale portions of the film with the optical density of other 
areas of interest in the scene. This procedure offers a number of advantages 
over other techniques using standard instrumentation, in that, relatively 
unskilled persons can be used in collecting the data and a permanent visual 
record of the test and environment is provided for future reference. 

The intended outcome of this work will hopefully provide a set of guide- 
lines or lighting standards that the underground non coal raining industry can 
utilize to improve the safety and productivity of their work environment. A 
more detailed discussion of this Bureau work is presented in a separate paper 
of these proceedings 2 . 



94 




FIGURE 13. - Gray scale card used in photographic technique 
for determining reflectivity of mine surfaces. 



95 



REFERENCES* 

1. Beckett, Glenn., UMWA/BCOA Mine Illumination Survey. 

2. Crooks, William H. , and Peay, James M. , Definition of Illumination 
Requirements for Underground Metal and Nonmetal Mines. 

3. Crouch, C. L. , Disability Glare Studies on Underground Mine Personnel, 

4. Guth, Sylvester, K. , Discomfort Glare Sensitivity of Underground Mine 
Personnel. 

5. Hottinger, David D. , Illuminating Large Surface Mining Machines, 
Problems, and Solutions. 

6. Wahl, Martin H. , Lighting for Large Mobile Surface Mining Equipment. 

7. Yingling, Jon C, Coal Industry Experience with Mine Illumination 
Systems: Maintenance Requirements and Personnel Acceptance. 



*Note: All references are contained in these proceedings 



96 



TITLE OF PAPER: 



Underground Lighting 
Acceptance Procedures 



AUTHOR: Mr. Freddy M. Huffman, P.E. 
U.S. Department of Labor 
Beckley Electrical Testing Laboratory 
Beckley, West Virginia 



Mr. Huffman received a B.S. Degree in electrical engineering from the 
West Virginia Institute of Technology, and is a Registered Professional 
Engineer in the state of West Virginia. He has five years experience 
with the Mine Safety and Health Administration-Technical Support in the 
design, development, and testing of mine illumination systems, and one 
year with Coal Mine Safety and Health. Most recently he has been involved 
in longwall lighting system approvals and photometer calibration. 



CO-AUTHOR: Mr. William H. Beasley 
Mechanical Engineer 
MSHA-Technical Support 
Beckley, West Virginia 



97 



UNDERGROUND LIGHTING SYSTEM ACCEPTANCE PROCEDURES 

by 
Freddy M. Huffman 1 



ABSTRACT 

Federal regulations on underground coal mine lighting were issued in 
October 1976 and became effective in July 1978. These regulations established 
minimum illumination requirements and outlined procedures by which a Mine 
Safety and Health Administration (MSHA) acceptance for such a lighting system 
can be obtained and the criteria MSHA uses when issuing Statements of Test and 
Evaluation (STE's). 

Methods and guidelines were adopted by MSHA's Beckley Electrical Testing 
Laboratory ( BETL) to implement the requirements for issuing STE's for under- 
ground coal mine lighting systems. STE's are issued for underground coal mine 
lighting systems, machine lighting, shortwall and longwall lighting, and 
stationary lighting. 

Acceptance of a lighting system depends on three major areas of consider- 
ation. First, it must be verified that the components of the system have been 
approved as permissible (will not ignite methane) and are suited for their 
intended use. Second, it must be determined that the system provides suffi- 
cient illumination for compliance with the lighting regulations. Third, the 
system must not create objectionable glare for the miners. 

INTRODUCTION 

Prior to 1969, equipment which traveled in excess of 4.0 km/hr (2.5 mph) 
was the only equipment in United States coal mines required to have luminaires 
installed. The only other required illumination found in U.S. coal mines was 
the coal miner's electric cap lamp. In 1969, Congress authorized the estab- 
lishment of minimum illumination standards for underground coal mines, basing 
the decision upon the following facts: 

1. The accident rate in U.S. coal mines was high due, in part, to the 
use of fast-moving, high-production equipment which operated in 
areas with restricted clearance. 



Electrical Engineer, U.S. Department of Labor, Mine Safety and Health Admin- 
istration, Technical Support, Approval and Certification Center, Beckley, 
West Virginia. 



98 



2. Research studies have shown that improved lighting in other U.S. 
industries has substantially decreased the accident rate. 

In 1969, illumination expertise and approved permissible area lighting 
hardware were in very limited supply in the U.S. coal industry. Six years of 
experimentation, research studies, and numerous U.S. Bureau of Mines research 
contracts produced some lighting expertise and a few fixtures still used in 
U.S. coal mines today. 

During initial installation of the new lighting systems on equipment in 
1976 and 1977, problems were encountered due to glare. The lighting sources 
were found to be too bright for the confined work areas. To effectively 
minimize the discomfort glare experienced by coal miners, MSHA required the 
use of diffusers or louvers in conjunction with the lighting fixtures. 

A procedure was needed whereby coal mine operators could purchase com- 
plete lighting systems and be assured that these systems met all the criteria 
of the Federal lighting regulations. Accordingly, MSHA developed and imple- 
mented the STE program for evaluation of a proposed underground coal mine 
lighting system to ensure that they meet all the requirements of the Code of 
Federal Regulations. The lighting system is evaluated for glare and the 
permissibility of the lighting component arrangement placed on the coal mine 
equipment . Evaluation for permissibility is an integral part of the program 
because all electric-powered coal-extraction equipment used in the working 
places of U.S. coal mines is required to be permissible. That is, any compo- 
nents that are added to the equipment must maintain the permissibility. 

Lighting arrangements that meet the criteria for an MSHA-accepted light- 
ing system are issued an acceptance letter called a Statement of Test and 
Evaluation (STE). For each STE-approved lighting system, a metal tag con- 
taining identification information is affixed to the machine. 

The amount of illumination required for an STE was determined by U.S. 
Bureau of Mines research contracts on the minimal illumination necessary to 
safely perform underground mining tasks. Recommendations from these research 
contracts were for the coal surfaces to be illuminated to approximately 
0.20 Nit (0.06 fL) surface brightness. Such surface brightness would enhance 
the miner's vision from the tunnel effect (cap lamp only) to total peripheral 
vision, enabling the miner to detect movement much more easily. Yet the 
0.20 Nit (0.06 fL) level of surface brightness is low enough that a miner can 
easily adapt to an even lower light level, as when traveling from an illumi- 
nated face area to a coal mine area which is not required to be illuminated 
apart from the miner's cap lamp. 

Due to the more complex instrumentation needed and the difficulty of 
taking sufficiently accurate reflected light measurements, incident light 
measurements are used for the issuance of STE ' s . Using an average coal mine 
reflectance of 4 percent, the surfaces required to be illuminated by the 
lighting standards must have an average of 21.5 Lux (2 fc) of incident light 



99 

on any 0.37-m 2 (4-sq-ft) area to receive an STE . Applications for STE accept- 
ance are submitted to BETL by lighting manufacturers, mining equipment manu- 
facturers, and coal mine operators. 

An STE application must contain the following: 

!• Machine Layout Drawing - This drawing contains the mining machine 
dimensions, the lighting fixture locations, the mounting angle of 
each fixture, and the type of diffusion or shielding applied to each 
lighting fixture. 

2. One-line Diagram Drawing - This drawing shows all the permissible 
components of the complete lighting system connected by one line as 
they would be installed on a mining machine. 

3. Electrical Schematic Drawing - This drawing shows the purchaser of 
the lighting system how to electrically connect all the lighting 
fixture hardware . 

4. Data - Data of all the required surfaces to be illuminated by the 
lighting regulations can be taken from actual machines or machine 
mock-ups. The data can be obtained from any one of these three 
sources : 

(1) Field data taken by a representative of BETL; 

(2) Laboratory data taken in BETL's mine simulator located at 
Beckley, West Virginia; 

(3) Laboratory data taken at an applicant's approved laboratory. 

5. Electrical Drawing (longwall and shortwall applications only) - This 
drawing is used to ascertain that the lighting system meets all the 
electrical requirements for area lighting, i.e., maximum of 70 VAC 
to ground, overload and ground fault protection, and resistance 
grounding . 

6. Short-circuit Calculations (longwall and shortwall applications 
only) - The calculations are used to ascertain that the lighting 
fixture circuit is protected by a suitable overcurrent device 
against minimal short-circuit currents. 

MACHINE-MOUNTED LIGHTING SYSTEMS 



Present STE requirements for machine-mounted lighting systems are as 
follows : 



100 

1. Conti nuous Mining Machines and Coal-loading Machines (Figure 1) 

In working places 1.1 m (42 in.) and above in which con- 
tinuous mining machines and coal-loading equipment are 
operated, the areas which are required to be illuminated 
are as follows: 

(1) The coal face; 

(2) The ribs, roof, floor, and exposed surfaces of mining equipment 
which are between the face and the inby end of the shuttle car 
or other conveying equipment while in position to receive 
material . 

To provide more direct light upon the coal face and allow the most effi- 
cient use of the available light, light measurements are not to be taken of 
the floor area between the cutter boom hinge pin or gathering head hinge pin 
and the coal face . 

In working places below 1.1m (42 in.) in which continuous 
mining machines and coal-loading equipment are operated, 
light measurements are made within an area the perimeter 
of which is 1.5 m (5 ft) from any part of the continuous 
mining machine when measured parallel to the mine floor. 

Operators of remote-controlled continuous mining machines experienced 
glare from the machine-mounted lighting fixtures located closest to the oper- 
ator's locations. Since the operator of such machines is not confined to a 
location on the machine, the placement of any present-day lighting fixtures 
which would light up the coal roof, rib, and floor surfaces to the 21.5-Lux 
(2 fc) value became a source of discomfort due to glare. For this reason, STE 
acceptances of remote-controlled continuous mining machines operating in 
mining heights of less than 1.1m (42 in.) are issued without taking light 
measurements on the right side outby the center of the main frame of the 
mining machine (Figure 2). 

Present technology will not permit installation of light fixtures on 
rope-propelled, auger-type continuous mining machines in which miners are 
required to go inby the machines to set jacks or timbers without creating 
discomfort due to glare for the jacksetters or timbermen. Therefore, pending 
the development of glare-free illumination systems for these machines, illumi- 
nation is not currently required in working places in which rope-propelled, 
auger-type continuous mining machines are operated if jacksetters or timbermen 
are required to work inby the machine operator. 



101 



■^■/j:i* t^: 




«v 



s^-A-^^-r-cp-^-^^^ - 






FIGURE 1. - Loader or continuous miner. The area to be illuminated is 
from the face to the outby end of the bumper. 




» 



&Z^^C%±'tt<&ZZ^tt & ~£-;~* 



/v 



FIGURE 2. - Remote-controlled continuous mining machine. The area to be 
illuminated is from the bumper to the face on the left side 
of the machine and from the center of the main frame to the 
face on the right side of the machine when operated in seam 
heights less than 1.1 m (42 in.). 



102 

2. Self-loading Haulage Equipment and Other Self-propelled Veh icles, 
such as scoops, shuttle cars, and load/haul/dump vehicles 

A coal surface equal in height and width to the machine, 
and 3.0 m (10 ft) from the machine in either direction of 
travel, must be illuminated to 0.20 Nits (0.06 fL) . 

Many of the scoops and other laod/haul/dump vehicles operate in coal 
seams where heights are not more than 15 to 20 cm (6 to 8 in.) above the 
height of the equipment. The confined clearances above the machine, 
undulations of the coal seam, and the installation of roof support material, 
such as cross headers — all these factors made the placement of lighting 
fixtures on top of such equipment virtually impossible. Therefore, in 
instances where the height of the coal does not permit installation of light 
fixtures on top of these vehicles, the areas to be illuminated should be as 
shown in Figure 3. 

3. Cutting and Drilling Equipment (Figure 4) 

In working places 1.1 m (42 in.) and above in which cut- 
ting or drilling equipment is operated, the areas which 
are required to be illuminated are as follows: 

(1) The coal face; 

(2) The ribs, roof, floor, and exposed surfaces of mining 
equipment which are between the face and a point 1.5 m 
(5 ft) outby the machine. 

In working places below 1.1 m (42 in.), light measurements 
are made within an area the perimeter of which is 1.5 m 
(5 ft) from any part of coal drills and cutting machines 
when measured parallel to the mine floor. 

4. Roof Bolting Machines (Figure 5) 

In working places 1.1 m (42 in.) and above in which roof 
bolting equipment is operated, the areas which are illumi- 
nated are as follows: 

(1) Where the distance from the floor to the roof is 1.5 m 
(5 ft) or less: the coal face, ribs, roof, floor, and 
exposed surfaces of mining equipment which are within 
an area the perimeter of which is a distance of 1.5 m 
(5 ft) from the machine when measured parallel to the 
floor . 

(2) Where the distance from the floor to the roof is more 
than 1.5 m (5 ft): the coal face, ribs, roof, floor, 
and exposed surfaces of the bolting equipment which 



103 



Illumination is not required 
in this area. 



FIGURE 3, 




- Scoop. The areas to be 
illuminated are desig- 
nated by A and B when 
coal seam height will 
not permit the instal- 
lation of light fixtures 
on top of the machine. 







FIGURE 4. - Cutting machine. The area to be illuminated is from 
the face to 1.5 m (5 ft) outby the machine. 



104 



X 



V 



Jjrqggf 



■4-H 




gir-n |d i 



7 



^ 



/ 



\ 



y 



FIGURE 5. - Roof bolting machine. The area to be illuminated is 
1.5 m (5 ft) or mining height, whichever is greater. 




r/s .».■.. *.V-«,»o.»»./Yvs>».>'* I -*J":'.'-'. w *.rk--»*' . -'/•/» .4^ *-l J .-)V< 



FIGURE 6. - Shortwall system. The area to be illuminated is 
from the face to the gob side of the travelway. 



105 



fall within an area whose perimeter is equal to the 
distance from the floor to the roof except for the 
area to the rear of the machine. The area to be rear 
of the machine for a distance of 1.5 m (5 ft) when 
measured parallel to the floor must be illuminated to 
21.5 Lux (2 fc) . 

(3) Light fixtures installed adjacent to supply trays on 
dual-head bolting machines create objectionable glare 
to the machine operator and helper. Therefore, to 
allow removal or repositioning of these light fix- 
tures, the lighting system is considered to be in 
compliance if the required level of light is provided 
as determined by illumination measurements made with 
the drill heads either together or separated approxi- 
mately 2.4 m (8 ft) and in position to drill holes or 
install roof bolts. 

In working places below 1.1m (42 in.) in which roof 
bolting equipment is operated, lighting measurements are 
not taken within the area in front of and to the side of 
the roof bolting machine operator's position. This does 
not apply to roof drills that are an integral part of a 
continuous mining machine. 

SHORTWALL AND LONGWALL LIGHTING SYSTEMS 

1. Shortwall Mining Equipment (Figures 6 and 7) 

The area to be illuminated is between the gob side of the travelway and 
the side of the block of coal from which coal is being extracted for the 
entire length of the sel f- advancing roof support system. 

The areas to be illuminated would include the face, roof, 
floor, and exposed surfaces of mining equipment between 
the face and the gob side of the designated travelway. 
This illumination may be accomplished by stationary light- 
ing only as shown in Figure 6 . 

The required areas of shortwall mining systems utilizing 
continuous mining machines (see Figure 7) may be illumi- 
nated as follows: 



(l) For the section of the shortwall from which coal is to 
be extracted, the illuminated area is between the gob 
side of the travelway and the face. 



106 




FIGURE 7. - Shortwall plan view. The area to be illuminated is 
from the gob side of the travelway to the face. 



^■^.T:.x:-r.^.^:--.^ 



•^YiUt.'J 




•-V *- V- 7- ^-v-'.t v«r .».*"-<£ 



V 






A 



I 



FIGURE 8. - Longwall system. The area to be illuminated is from 

the face to the gob side of the travelway. Designated 
Travelway "A", the area to be illuminated is A'. 
Designated Travelway "B", the area to be illuminated 
is B ! . 



107 



(2) The continuous mining machine shall have machine- 
mounted lighting fixtures installed in accordance with 
an STE. 

(3) For shuttle car haulage systems, the shuttle car must 
have an STE illumination system installed. 

Longwall Mining Equipment (Figures 8, 9, and 10) 

In seam heights 1.1 m (42 in.) and above, the following 
areas are required to be illuminated: 

(1) The face; 

(2) The area between the gob side of the travelway and the 
side of the block of coal from which coal is being 
extracted for the entire length of the sel f- advancing 
roof support system; 

(3) The control station and the headpiece and tailpiece of 
the face conveyor; 

(4) The roof and floor for a distance of 1.5 m (5 ft) 
horizontally from the control station, headpiece, and 
tailpiece . 

In seam heights below 1.1 m (42 in.), problems have been 
encountered in illuminating the coal face and face con- 
veyor to 0.20 Nits (0.06 fL) in longwall mining instal- 
lations operating in coal seams under 1.1 m (42 in.) in 
thickness . The problems have been caused by the lack of 
sufficient clearance between the bottom of the roof 
support chocks and the side of the face conveyor, leaving 
little or no space through which light fixtures installed 
on the chocks can cast light on the face conveyor or the 
coal face. Therefore, in determining compliance with the 
illumination requirements for longwall mining instal- 
lations operating in coal seams less than 1.1 m (42 in.) 
in thickness, measurements will not be taken on the face 
conveyor or the coal face. Measurements will be taken the 
entire length of the travelway. The following areas are 
required to be illuminated: 

(1) The control station and the headpiece and tailpiece of 
the face conveyor; 

(2) The roof and floor for a distance of 1.5 m (5 ft) 
horizontally from the control station, headpiece, and 
tailpiece . 



108 




Areas to be Illuminated 




FIGURE 9. - Headpiece and tailpiece. The area to be illuminated 
is 1.5 m (5 ft) around the headpiece and tailpiece. 




FIGURE 10. - Control station. The area to be illuminated is 
1.5 m (5 ft) around the control station. 



109 



AREA LIGHTING SYSTEMS 

The same areas are required to be illuminated by area lighting systems as 
by machine-mounted lighting systems. Although BETL has received several 
applications for area lighting, there have been no STE acceptances issued. 
Area lighting in U.S. coal mines has not been successful for three reasons: 

1. The permissible power supplies are heavy and are especially diffi- 
cult to maneuver in lower coal seams. 

2. The constant hanging or routing of the electric cables to the light- 
ing fixtures would diminish safety to the miners due to possible 
electric shock hazards. 

3. The constant moving of the lighting fixtures and lighting fixture 
cables during the coal-extracting process would probably necessitate 
an additional worker per working section just for the movement of 
the lighting fixtures. 

CONCLUSION 



There are seven major U.S. manufacturers of lighting fixtures. Different 
lighting fixtures have different design advantages so that mine operators have 
a selection from which to choose the one that best suits their mining needs. 

In some of the lighting fixtures which require ballastry, the ballast is 
an integral part of the approved fixture while other lighting fixture designs 
place the ballasts in a separate permissible enclosure. 

Mine operators and maintenance personnel have had difficulty in main- 
taining systems containing ballast hardware. In addition, the mercury vapor 
and high-pressure sodium lamps experience lamp outages during appreciable dips 
in voltage. Such dips in voltage are common in U.S. coal mine working places 
and are the result of starting up large motors on board the coal-extraction 
equipment, such as the two ripper head motors on the continuous mining 
machines. These two ripper head motors are usually 126.75 to 152.1 horsepower 
(125 to 150 Hp) each. These lighting systems, designed with high intensity 
discharge (HID) lamps, generally tend to be brighter than lighting systems 
utilizing other lamp designs. Hence, MSHA receives more glare complaints 
about the HID systems and such systems have had less miner acceptance. 

U.S. mine operators and maintenance personnel have also had difficulty in 
maintaining fluorescent lighting systems where the ballast is not an integral 
part of the lighting fixture. 

STE-approved lighting systems designed with incandescent lighting fix- 
tures have had an increasing acceptance in U.S. coal mines today for three 
main reasons — (l) lower initial cost; (2) ease of maintenance; and (3) rug- 
gedness of the lighting fixture. 



110 

Mine operators are not required to obtain STE-approved systems and may 
elect to design and install systems of their own which meet all the criteria 
of the lighting regulations. BETL is available to help the mining industry 
with any lighting problems encountered in the effort to provide a safer and 
more productive environment for the Nation's coal miners. 



Ill 



TITLE OF PAPER: 



Illumination in South African 
Gold Mines 



AUTHOR: Mr. R. Hemp 

Rand Mines Limited 
Marshalltown, South Africa 



Mr. Hemp holds the position of Group Ventilation Engineer, and has 
worked for Rand Mines for the last 20 years. During this period he has 
worked in mine ventilation, including airflow, refrigeration gases, and 
dust. More recently his responsibilities have been expanded to include 
noise and illumination. 



Mr. Hemp is a member of the TC-4.10 Mine Lighting Committee, 



112 



ILLUMINATION IN SOUTH AFRICAN GOLD MINES 

by 
Roger Hemp 1 



ABSTRACT 

Some statistical information on men at work, production and productivity 
is used to explain both the interest in and the problems associated with 
illumination in South African gold mines. The present statutory requirements 
regarding mine lighting are stated, and some information is given on present 
illumination methods and conditions. The occurrence of inflammable gas in 
the gold mines is described, and while this is not a problem on some mines, 
there are mines where fairly large quantities of gas are encountered. This 
does not, however, have a very significant effect as far as most underground 
light sources are concerned. 

Work which has been done on mine lighting in South Africa is described. 
This includes work by the Chamber of Mines, by one of the mining groups, and 
by the South African National Committee on Mine Illumination. This work in- 
cludes investigations into visual acuity, colour blindness, and dark adapta- 
tion in black men, who form the great majority of the underground workers in 
South African mines; the development of an improved miners' cap lamp; some 
experimental work on stope illumination; and the progress which is being made 
in developing a set of recommendations for mine lighting. 

INTRODUCTION 

The South African mining industry employs a large number of workers. 
Statistics (1) for the calendar year 1979 indicate that a total of about 
772,000 men are at work, of these about 453,000 work underground, while 
319,000 work on surface. Of the 453,000 underground workers, about 333,000 
work on gold mines, 51,000 on coal mines, and the remaining 69,000 on other 
mines. These figures show that just under 74 percent of the men working 
underground in mines in South Africa are working on gold mines. 

The literature on mine illumination indicates that most work has been 
done on the illumination of coal mines and of other highly mechanised mines. 
While determined efforts are being made to change the situation, South 
African gold mines are at present not highly mechanised. Thus, while there 
is obviously much published work on mine illumination which is relevant to 



1 Group Ventilation Engineer, Rand Mines Limited, Johannesburg, South Africa 



113 

the illumination of gold mines, there are many situations underground in gold 
mines where equipment and techniques developed for mechanised mines are of 
little or no value. 

Some production figures will emphasize the lack of mechanisation on gold 
mines. During 1979, the gold mines milled some 86 million tons of gold- 
bearing rock. This amounts to just under 260 tons per annum per underground 
worker. South African coal mines, on the other hand, produced just under 104 
million tons of coal during 1979. While the fact that some of this production 
as from opencast operations makes it difficult to calculate a corresponding 
figure per underground worker, it is estimated that coal production from 
underground mines is at least 1,600 tons per annum per underground worker, or 
at least six times the gold mine figure. 

The low level of mechanisation in gold mines is primarily due to the 
nature of the ore deposit and the characteristics of the surrounding rock. 
The gold, sometimes accompanied by uranium, is contained in narrow conglom- 
erate reefs, ranging in thickness from a few centimetres to several metres. 
The surrounding rock, and indeed the reef deposits themselves, are very hard, 
abrasive rocks, and thus not suitable for the mechanised mining methods used 
in, for example, coal mines. The generally narrow reef deposits also preclude 
the use of methods developed for the mining of massive ore deposits. 

This situation has two important results as far as gold mine illumination 
is concerned. The first is the large number of men working underground, and 
the extent of this has been described above. The second is that there are a 
very large number of working places on any one mine, and as a result, there 
is an extensive network of shafts and haulages to serve the production areas, 
all of which ought to be properly illuminated. While this does present a 
problem of some magnitude, a far more serious problem is that of properly 
illuminating the working places themselves. 

The mining methods used make this a formidable problem. Virtually all 
the rock broken underground in gold mines is broken by blasting. This re- 
quires the drilling of vast numbers of drillholes, and the need to suppress 
siliceous dust means that water is used in fairly large quantities, probably 
something like one ton of water per ton of rock broken. The frequent blast- 
ing operations prevent the installation of permanent or semi-permanent light- 
ing in working places, and the wet and very rugged conditions mean that it is 
not practical to use mains-powered or cable-operated equipment. 

Some idea of the extent of the underground workings in gold mines can be 
gauged from the following statistics (2) . During 1979 there were, on average, 
some 3,400 working stopes on 39 gold mines; that is an average of just under 
90 stopes per mine. The actual range was from 2 to 600 stopes per mine. 
During the same period there were, also on average, about 3,600 development 
ends, or also about 90 per mine. Production figures averaged just under 
22,000 tons per annum per stope, and about 8,500 tons per annum per develop- 
ment end. 



114 



The above should help to explain the interest in illumination problems 
in gold mines, and hence the choice of subject matter for this paper. 

The paper will describe the present statutory requirements for mine illu- 
mination and will give some indication of the methods presently used, and 
some results of surveys carried out to establish existing illumination levels. 
Brief descriptions will be given of research work which has been carried out 
by the Chamber of Mines of South Africa, and the work which is presently 
being done by the recently formed National Committee on Mine Illumination 
will be described. 

STATUTORY REQUIREMENTS 

Chapter 15 of the Regulations made under the Mines and Works Act [Act 
No. 27 of 1956] deals with lighting, safety lamps and contraband. Most of the 
regulations in this chapter deal with flame safety lamps, with portable lamps 
[this includes miner's cap lamps] and with permanent lighting fittings, all 
in the context of safety in mines where inflammable gas is encountered. 

A few of the regulations do, however, deal in very general terms with 
illumination levels. These regulations are:- 

15.1 "No person shall work or travel or cause or permit any other 
person to work or travel in any unilluminated part of a mine 
or works unless he or such other person carries a light. 

15.2 "Adequate stationary lights shall be provided - 

15.2.1 during working hours at all established stations, landing 
and loading places and other similar places in vertical 
and inclined shafts, winzes and planes where winding is 
being carried on; 

15.2.2 at night at all places on surface where work is being 
carried on. For the purpose of this regulation and 
regulation 15.3.2 "night" shall mean that period of time 
from half-an-hour after sunset to half-an-hour before 
sunrise. 

15.3.1 "All places where winding, driving, pumping or other machinery 
is erected, in the proximity of which persons are working or 
moving about, shall be so lighted that the external moving parts 
of such machinery whilst in operation are clearly visible. 

15.3.2 "At all times underground and at night on surface the leading 
end of every moving train operated by a locomotive or any other 
power-driven vehicle, as well as every moving locomotive or 
other power-driven vehicle unattended to trucks or other 



115 

conveyances, shall be provided with an effective bright light 
shining in the direction of travel." 

While these four regulations are specific about the places which must be 
illuminated, the illumination levels which must be achieved are not defined 
in scientific terms at all, and depend upon such subjective phrases as 
"adequate," "clearly visible," and "effective bright light." 

It must also be noted that the regulations do not require all places in 
a mine to be illuminated by sources other than the cap lamp. There are many 
working places in a gold mine which do not fall under the provisions of regu- 
lations 15.2, 15.3.1 and 15.3.2, and regulation 15.1 thus requires that in 
these places the miner's cap lamp must be used and may be the sole source of 
illumination. 

PRESENT ILLUMINATION METHODS AND CONDITIONS 

A short answer to the question of how gold mines are illuminated at 
present would be that they comply with the present Regulations, as described 
in the previous section. However, this statement does not give very much in- 
formation, and an attempt will be made in this section to give some details, 
albeit still in general terms. 

Before giving any details of installations, or information on illumina- 
tion levels, the situation regarding the presence of inflammable gas will be 
described. 

South African gold mines range from mines in which significant quantities 
of methane have never been found [and which are mines in which naked flames 
are allowed], to mines in which large quantities of methane are found; so 
large in at least one instance that a methane drainage system is installed, 
and the collected methane is used on surface for steam raising in a boiler 
installation. 

While South African mining regulations made provision for a mine to be 
declared "fiery" there are, to the best of the writer's knowledge, no gold 
mines which have been declared as completely fiery mines, although any gold 
mine which does encounter methane will generally be required to comply with 
some of the regulations applying specifically to fiery mines. 

These regulations will generally restrict equipment which may be in- 
stalled at or near current working places to that which is either flameproof 
or intrinsically safe, but will not place restrictions on equipment installed 
in downcast shafts and main intake airways. Because hoisting, travelling, 
and the transportation of materials is almost without exception done in down- 
cast shafts this means that the luminaires used for the permanent lighting 
installations mentioned in Regulations 15.2 and 15.3.1 need not generally be 
flameproof. 



116 



The illumination of such places as electrical sub-stations, pump stations, 
shaft stations, underground workshops, haulages and winch sites is generally- 
achieved using either incandescent or fluorescent lamps, sometimes in lumi- 
naires, but often, particularly with incandescent lamps, just using the bare 
lamp. In some situations other lamps are used, such as tungsten halogen, 
mercury vapour, or other discharge lamps. One installation using high- 
pressure sodium lamps to illuminate an underground winding engine chamber has 
been described(3) . 

Most haulages which are illuminated use incandescent lamps. While the 
capital costs of these are low, the operating costs are high. As in most 
other countries, electrical power costs in South Africa are increasing stead- 
ily, and one very rough calculation indicated that, for equal illumination 
levels, a system using fluorescent lamps instead of incandescent lamps was 
justified on economic grounds. The fluorescent lamp system obviously had a 
much higher capital cost than the incandescent lamp system, but the savings 
in operating costs were sufficient to offset the capital cost difference 
within two years. 

Some idea of the illumination levels existing underground in gold mines 
can be obtained from two different sources. The first is a paper by van 
Graan et al(4) which gave the results of surveys carried out by the staff of 
the then Human Sciences Laboratory of the Chamber of Mines of South Africa. 
The following table gives the average illuminance measured in various working 
places. 



Average Illuminance, lux 
1971 work (ref 4) 1981 work (ref 5) 



Electrical sub-stations, 

Conveyor belts , 

Pump stations 

Shaft stations 

Workshops 

First aid stations , 

Tips , 

Winches 

Waiting places , 

Haulages 



82 

64 

56 

48 . 

44 

40 

34 

27 

17 

7,5 



67 
66 

67 
71 
70 
47 
36 
17 
19 
18 



The table also gives the results of some more recent measurements. 
These measurements are reported by Schroder and van der Walt(5), and are 
averages of routine measurements made by staff of the environmental control 
departments on the mines. 



117 



While some differences are apparent in the average figures given in the 
above table, these differences are not very large, and it can be concluded 
that there has been little change in illumination over the period between the 
two surveys. 

It is important to appreciate that the tabulated figures are averages. 
Very considerable variations occur, both on a particular mine and between 
different mines. This is illustrated in Figure 1, which shows frequency dis- 
tributions of observed illuminance values at winches for the two surveys. 



(O 



% 

cc 

UJ 
(O 
CD 

o 
o 



1971 SURVEY 
1981 SURVEY 



aw 


r — ' 


1 


1 


1 






1 

i 












1 








30 
20 


; 








1 i 

i i 

i i 

i 

i 

i i 

i i 

i i 

i 

1 










1 1 
i i 
i i 
i i 
i 
i 


. . 








10 


i 

1 i 
I L 


1 1 

i i 




1 ill 
1 1 1 
J l 1 

1 














i 
i 





i 
I 
i 

_■ 




O 




, 


1 


— i 
1 
1 


i 1 



50 



100 
ILLUMINANCE LUX 



150 



Figure 1. 



Neither of the two surveys gave the results of illumination measurements 
in stopes or development ends. The reason for this is that, as mentioned 
earlier, the sole source of light in these places is the miner's cap lamp. 
Under these circumstances, it is an extremely difficult problem to obtain 



118 



measurements that adequately represent the illumination conditions in the 
working place, van Graan et al(4) did quote a value of between 2 and 4 lux 
for stopes, but this figure was based upon a study of cap lamp performance 
and not upon measurements taken in the stope. 

INVESTIGATIONS INTO MINE ILLUMINATION 

Investigations into mine illumination in South Africa have been under- 
taken by three different bodies. 

For many years, the Human Sciences Laboratory, now the Industrial Hygiene 
Branch, of the Research Organisation of the Chamber of Mines of South Africa 
has taken an active interest in mine illumination, and has undertaken various 
research projects. The work mentioned earlier [van Graan et al(4)] is part 
of this, and other work will be described in this section of the paper. 

Some of the mining groups have also investigated some aspects of mine 
illumination, and some work on stope illumination carried out by the then 
Union Corporation group will also be mentioned. 

While South Africa has been a member of the CIE technical committee on 
mine lighting [TC-4.10] for some time, it was only early in 1980 that a 
national committee was formed. This committee, the National Committee on 
Mine Illumination, is busy compiling a set of recommendations for illumination 
in South African mines. At present, this work is confined to gold mines, and 
while it is proceeding well, it has not yet reached even the stage of a draft 
document. Some details of the progress of this work will be mentioned. 

Chamber of Mines of South Africa 

The work done by the Chamber of Mines falls under two distinct headings. 
The first involves investigations into visual acuity, dark adaptation and 
colour perception, while the second involves the development of improved 
miner's cap lamps. 

The great majority of underground workers, whether on the gold mines 
alone, or on all South African mines, are black. Reference 1 indicates that 
the proportion is just on 94 percent. The investigations into visual acuity, 
dark adaptation and colour perception have all used black men as subjects. 

The work has been reported on by van Graan et al(6) and by van Graan (7 ) . 
Tests on visual acuity under different illumination levels, and on colour 
blindness, were conducted on a total of 500 men, whereas 60 men were tested 
for dark adaptation. 

The visual acuity tests involved reading a Snellen chart under various 
conditions of illumination, when the subjects were either light-adapted or 



119 



dark-adapted. It was concluded that the subjects tested had, in general, 
superior vision, but that, as would be expected, visual acuity decreased as 
the light level decreased. One way in which these results were illustated 
was by plotting graphs showing how the percentage of men having 6/6 vision 
varied with illuminance. These results are shown in Figure 2. 



100 



80 



Q 

> 

CO 

s 

to 

X 
H 

? 

uj 40 

S 

u. 
o 

b 



60 



20 



LIGHT ADAPTED 
DARK ADAPTED 













^ 


^ 


•zzz 


>~" 








fi 


S 


Z 


' 












// 


f 
















4 


f / 







































10 



20 30 



60 100 200 300 600 1000 



ILLUMINANCE LUX 
(LOG SCALE) 

Figure 2. 



Color blindness tests utilized the standard Ishihara colour blindness 
test chart and the results showed that only 7 out of the 500 men (1,4 per- 
cent) suffered from colour blindness. This figure is significantly lower than 
the figure of around 8 percent generally quoted for Caucasian males. 



120 



This low incidence of colour blindness amongst black males is generally 
supported by other work, quoted by van Graan et al(6) , but one study revealed 
an incidence of 34 men out of 372 tested, or just over 9 percent. 

Dark adaptation times varied from 11 minutes to 105 minutes, with an 
average of just under 33 minutes. These times appeared to be generally longer 
than those normally quoted. A maximum time of about 40 minutes is usually 
quoted for complete dark adaptation, whereas this study indicated that only 77 
percent of the men tested were dark adapted within 40 minutes. 

Following on from this work the Chamber of Mines developed standard 
methods for visual acuity and colour blindness testing [van Graan et al(8) and 
van Rensburg et al(9)]. An important aspect of this, and one which the 
authors stress, is the necessity for visual acuity testing to be done under 
low illuminance levels. 

While the above work has resulted in some very valuable information on 
visual acuity, dark adaptation and colour perception, no work has been done 
either on visual perception or on the visual performance required underground, 
both from the standpoint of the job and from safety requirements. This is an 
aspect which should be investigated, for, as an example, Grundy (10) has stated 
that there is an indication that black men require higher illuminance values 
than those required for Caucasians. On the face of it, this seems to conflict 
with the conclusions of van Graan et al(6) that the visual acuity of their 
subjects was high. 

Further work done by the Chamber of Mines has involved an investigation 
into the colours and contrasts necessary for warning signs underground 
[Davidoff et al(ll)]. 

The work done by the Chamber of Mines on miner's cap lamps has covered 
two aspects. The first involves the compilation of a code of practice for the 
repair, maintenance, and charging of cap lamps [Blignaut (12) ] . 

The second aspect has been a collaborative one with one of the local 
suppliers of cap lamps, and has involved the development of an improved cap 
lamp. This work has been described by Taylor (13). 

The new cap lamp is now being used on a test basis on two gold mines, and 
full-scale manufacture will be achieved later this year. 

The cap lamp uses a new headpiece fitted with a tungsten halogen bulb 
(4V, 1A) . Lumen output is considerably greater than present lamps. A vital 
part of the new lamp is the greatly improved lead-acid battery. This is a 
completely sealed unit with a 16Ah rating, compared with the lOAh rating of a 
conventional battery. The mass of the new battery is significantly lower, 
1,96kg instead of 2,24kg. 



121 



Figure 3 shows some preliminary illumination figures, and compares the 
new lamp with the old. 




NEW LAMP 



VALUES ARE ILLUMINANCE (LUX) AT A DISTANCE OF 2m 



100 



200 



300 



400 



MILLIMETRES 



OLD LAMP 




Figure 3 



122 



Union Corporation 

Earlier on the work done by the then Union Corporation group on stope, 
illumination was mentioned. In this work several compressed air-driven lamps 
were used for general illumination in a stope. Compressed air is used very 
extensively on all gold mines, primarily for drilling. While no figures are 
available of the illuminance values achieved, a very interesting attitude sur- 
vey was conducted amongst the men working in the stope [Melamed et al(14)]. 

This attitude showed that most men preferred to work with extra illumina- 
tion, feeling that this made their job easier and more safe. The main 
negative comment was that the lamps were perceived as adding to the heat in 
the stope, probably because light is often associated with warmth. In actual 
fact, a compressed air driven lamp will provide slightly cooler conditions in 
the stope. 

National Committee on Mine Illumination 

The National Committee on Mine Illumination consists of sixteen members; 
they are drawn from both the mining industry and the lighting industry, the 
mining industry representatives being drawn from both the mining groups and 
the Chamber of Mines. The committee's work covers two main aspects. The 
first is naturally to collaborate with the international committee, TC-4.10, 
while the second, as mentioned earlier, involves the formulation of a set of 
recommendations for the illumination of South African mines. These two 
activities obviously overlap. 

For the reasons mentioned in the introduction to this paper the committee 
is at this stage concentrating on gold mine problems, and while this work is 
proceeding well it has by no means reached finality, and the information given 
here must be regarded as tentative. 

A starting point for establishing recommendations for mine illumination 
was the obvious one that illumination is necessary in all places where men are 
required to work or travel. For convenience working places and travelling 
ways in the mine were considered to fall into two basic categories. 

The first category includes all those areas where it is both practical 
and advisable to install permanent lighting installations. This thus includes 
all areas where men frequently work and travel, and where no blasting takes 
place. The second category covers areas where, for safety, economic, or 
practical reasons lighting installations cannot be permanent. This category 
thus includes 

a. all current working areas, where the regular blasting 
operations make it impossible to install permanent 
lighting installations. 



123 

b. areas such as airways in which no regular travelling 
takes place, vertical shafts, haulages, and crosscuts 
no longer in regular use, etc. The only time illumi- 
nation is required in these areas is when men do have 
to travel through them to work in them, and at these 
times the cap lamp is generally quite adequate. 

It was envisaged that the recommendations should, first of all, provide a 
list of all of the possible areas in a gold mine, divided into the categories 
described above. An examination of the type of work done in the various areas 
would make it possible to recommend suitable illumination levels for these. 

While the above information should be all that is necessary for a light- 
ing engineer to design suitable lighting installations it was felt very 
strongly that additional guidance should be given. This is because while some 
lighting installations in such places are winding engine chambers, electrical 
substations, and pump stations are designed by lighting engineers, there are 
many lighting installations on gold mines [and indeed on all other mines in 
South Africa] which are not designed by lighting engineers, and it is imprac- 
tical to expect that they ever will be. All lighting installations are in- 
stalled by mine engineering staff, sometimes according to mine standards, 
sometimes as determined by the mine electrical engineer, section engineer, or 
electrical foreman. For both of the above situations, the committee felt that 
the recommendations should contain sufficient information about lamps and 
luminaires to enable the mine to establish its own standards, and to assist 
the engineer who does not have specialist knowledge in illumination to design 
an installation. 

Other aspects of the recommendations cover miner's cap lamps, lighting 
systems for vehicles and mechanical equipment, emergency lighting systems, and 
warning notices and signs. 

The present position is that the list of working places has been drawn 
up, and tentative illuminance values have been allocated to these. Informa- 
tion on lamps and luminaires is nearly complete, and a draft set of require- 
ments for miner's cap lamps has been compiled. Finally, a list of areas 
where emergency lighting installations are necessary has been drawn up. 

The determination of required illuminance values was done as follows. In 
the first place it was decided to follow the South African Bureau of Standards 
code for interior lighting (15) in several respects. The first was in deciding 
to specify levels of illuminance rather than luminance. This is by far the 
most useful way for practical purposes, but it can obviously be criticised, 
and it is intended to do further work on this, particularly by establishing 
typical reflectivity values for underground situations. 

Illuminance values for all of the places in the permanent lighting cate- 
gory were taken from the SABS code, and the code was also used to specify 



124 



glare index values where necessary. In all of these areas it is intended that 
all of the illumination should be provided by permanent, mains operated 
installations, and that while all men would obviously continue to wear cap 
lamps, it would not be necessary for these to be used in these areas. 

Illuminance values for those working places in which blasting takes place 
regularly were considered on a somewhat different basis, mainly because it was 
difficult to find equivalent working places in the SABS code. These working 
places are mainly stopes and development ends. 

As mentioned earlier, at present the miner's cap lamp is almost without 
exception the only source of illumination in these areas. This was felt to 
be undesirable, particularly from the point of view of safety, for a man's 
peripheral vision is virtually nil under these conditions. Thus, while at 
this stage, there is no really suitable light source available, particularly 
for stopes, the committee felt that it was very important for general illumi- 
nation, albeit at a somewhat low level, to be provided in both stopes and de- 
velopment ends . 

The lack of a suitable source of general illumination for use in stopes 
and development ends is seen as a serious problem which should be given more 
attention. While no detailed specifications have been drawn up, it would seem 
that a diffuse source is essential so as to avoid glare in the generally 
narrow stopes. Stoping widths vary from 0,94m to 2,22m, with an average 
figure of 1,38m. 

The work on lamps and luminaires has covered such aspects as types of 
light sources, supply voltage, lamp caps, control gear, colour, lamp position, 
vibration, lamp life and lumen depreciation, restrike time, and light output 
and luminous efficiency. 

The requirements for miners' cap lamps cover aspects such as battery 
characteristics - mass, shape, comfort, mositure, shock, vibration, corrosion 
and abrasion resistance, and cable anchoring, similar factors for the head- 
piece, and performance characteristics - such as light output, beam geometry, 
burning time, reliability, and cycling life. Lamproom management is also 
covered. 

These are the portions of the recommendations that have been completed, 
at least in skeleton form, to date. No detailed information is given here 
because no finality has yet been reached. An important aspect of the work is 
that the committee intends to test the practicability of the recommendations 
by examining a section of a mine, and determining what changes would be 
necessary in order to comply with the recommendations, and what these changes 
would cost, both in capital costs and in operating costs. 

In conclusion, it should be noted that the work the committee has done 
shows that it is in complete agreement with views expressed ten years ago, 



125 



both by van Graan et al in their paper listed as reference 4, and by Martinson 
in a contribution to that paper. These views were that the only way to bring 
about improvements in mine illumination is to establish a standard code of 
practice, and that improvements in mine illumination can only lead to safer 
underground conditions and more productive work from the men working 
underground. 



ACKNOWLEDGEMENTS 

The author has benefitted greatly from all of the discussions with his 
colleagues on the National Committee on Mine Illumination, and it is a 
pleasure to be able to express thanks to them all here. 



Thanks are also due to Rand Mines Limited, both for their support in 
general, and for permission to publish this paper. 



126 

REFERENCES 

1. Mining Statistics 1979, Department of Mines, Republic of South Africa. 

2. Annual Ventilation Report for the Period October 1978 to September 1979. 
Chamber of Mines of South Africa, Internal Research Report, May 1980. 

3. "New light on work underground," Coal, Gold and Base Minerals of Southern 
Africa, October 1974. 

4. van Graan, C. H. , Greyson, J. S., Viljoen, J. H., and Strydom, N. B. 
Underground lighting in the gold mining industry. J. South African 
Institute of Mining and Metallurgy, January 1971. 

5. Schroder, H.H.E., and van der Walt, W. H. A summary of noise and illumi- 
nation returns from gold and coal mines. Chamber of Mines of South 
Africa, Internal Research Report, May 1981. 

6. van Graan, C. H., Greyson, J. S., Viljoen, J. H. , and Strydom, N. B. The 
visual acuity of bantu mine workers. Chamber of Mines of South Africa, 
Internal Research Report, March 1971. 

7. van Graan, C. H. A survey of underground illumination and visual acuity 
of the bantu in the South African gold mining industry. Proc. Mine 
Medical Officers' Association of South Africa, May 1971. 

8. van Graan, C. H., Johannes, C. H., Rabe, D. J., and Strydom, N. B. A 
guide to audio, visual and colour blindness testing in the mining 
industry. Chamber of Mines of South Africa, Internal Research Report, 
March 1975. 

9. van Rensburg, A. J., Strydom, N. B., and Kielblock, A. J. A guide to the 
assessment of visual acuity, colour perception and hearing in the mining 
industry. Chamber of Mines of South Africa, Internal Research Report, 
April 1981. 

10. Grundy, J. T. , Lighting levels with colour. SANCI Annual General Meeting 
1972. 

11. Davidoff, M. R. , Schutte, P. C, van Graan, C. H. , and Strydom, N. B. 
The influence of colour, contrast ratio and light intensity on visual 
perception. Chamber of Mines of South Africa, Internal Research Report, 
January 1978. 

12. Blignaut, P. J. Code of practice for miner's cap lamp assemblies 
incorporating lead-acid type batteries. Chamber of Mines of South 
Africa Internal Research Report, October 1976. 



127 



13. Taylor, C. J. A world first to cap them all. Coal, Gold and Base 
Minerals of Southern Africa, May 1981. 

14. Melamed, L. , and Cooke, H. M. Attitudes of black mineworkers to extra 
stope illumination. Chamber of Mines of South Africa, Internal Research 
Report, August 1976. 

15. Code of Practice for Interior Lighting. Part I: Artificial Lighting 
(Metric Units). SABS 0114: Part I - 1973. 



128 



TITLE OF PAPER: Mine Lighting Research and 

Development Work in Bulgaria 

AUTHOR: Eng. Gancho Ganchev 

Higher Institute of Mining and Geology 
Sofia, Bulgaria 



Mr. Ganchev graduated from the Higher Institute of Mining and Geology. 
After graduation he worked as an electrical engineer in the mines until 1965, 
when he joined the Higher Institute staff. He is a lecturer in the Depart- 
ment of Electrification of Mines, and the author of more than 20 papers in 
the field of electrification, automation, and lighting of the mines. 

Eng. Ganchev is a member of the Bulgarian National Committee of Illumi- 
nation, and since 1975 has been a member of the TC-4.10 Committee. 



129 



MINE LIGHTING RESEARCH AND DEVELOPMENT WORK IN BULGARIA 

by 
Gancho Ganchev 1 



ABSTRACT 

Mine-lighting research in Bulgaria has had an intensive development 
program in the last 5 to 6 years, involving investigations of the following 
main problems: 

1. Creating a method for measuring and inspection of mine lighting 
installations . 

2. Determining the reflection characteristics of coal mines and metal 
mines in view of mine-lighting projection by luminance. 

3. Creating standard levels of illumination of underground and open-pit 
mines . 

4. Creating luminaires for underground metal mines. 

5. Developing methods for mine-lighting design. 

The paper discusses the research done in Bulgaria on each of these 
problems, giving some of the basic considerations underlying the research and 
some results of the work done. 

TEXT 

Electric lighting in an underground mine in Bulgaria was for the first 
time applied in 1895, in the Pernik coal mine. Till the 9th September 1944 
mining in our country was underdeveloped . 

Today Bulgaria produces 30 million tons of coal — 77 percent of them from 
open pit mines . 

Mine developing gave rise to the electrification of mines as well as to 
mine lighting. 



■'•Chief Assistant, Higher Institute of Mining and Geology - Sofia 



130 



Mine lighting research has marked an intensive development in the last 5 
to 6 years. The main problems worked out in the investigation are: 

1. Creating a method for measuring and inspection of mine lighting 
installations . 

2. Determining the reflection characteristics of coal mines and metal 
mines in view of mine lighting projection by luminance. 

3. Creating standard levels of illumination of underground and open-pit 
mines . 

4. Creating luminaires for underground metal mines. 

5. Developing mine lighting design methods. 

The first problem; i.e. creating a method for measuring and estimating of 
mine lighting, arose from the necessity of controlling and inspecting mine 
lighting. 

It is necessary to define the least number of measurements and the appro- 
priate places to be measured in the mines with respect to deciding whether 
mine lighting is adequate to standards or not. To answer the above question, 
many illuminance measurements in different points and in various mines have 
been made . 

Figure 1 shows a diagram of the measuring. The illuminance was measured 
in the cross-point of a net with a step of one metre. 

When the mine working is long and narrow, the illuminance is measured 
along the axis of the floor and at every metre. 

On Figures 2 and 3, results obtained from measurements in a gallery in 
different metal mines are shown. 

After statistical data processing, the curves of frequency distribution 
are obtained. 

On Figures 4 and 5 are shown the curves of distribution for different 
working places; e.g. in chamber mining (a transformer substation, a water 
pumping chamber, a medical station, a locomotive depot, a workshop, etc.). 
The results are subordinated to normal distribution. The curves of illumi- 
nance distribution for a gallery are shown in Figure 6. They have binominal 
distribut ion . 

It is expedient to estimate the illumination according to the mean level 
of illuminance E and to the dispersion in case the results correlate with 
Gaussian distribution. 



131 







^lm^ 


, _lm 








e 

rH 








1 

e 

rH 


i 

r 











































Figure 1 



132 




133 




134 



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12 

11 

10- 
9- 
8- 
7- 
6- 
5- 
4 
3 
2- 
1- 



M 




2345678 9 10 E,lx 







Du — 


• 




40- 


M' A* 

V 




30- 


/ 
/.' 




20- 


/,' 




10- 


S/ 






V 

1 1 1 1 1 1 1 1 1 1 


— ► 



8 9 10 E,lx 



Figure 4 



i 


k. 






















K 




9~ 








8- 
7" 




// 

fi 






V 




- 


6- 




1 








\ 




5- 


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' 


\ 


4- 
3- 


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/ i 


. 










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>- 



1 11,4 20,8 E,lx 

9,2 15,8 24,6 



M 
50 

40H 

30 

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/ 



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l 



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M 



"1 i I I I l I I | i * 
1 11,4 20,2 E,lx 

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Figure 5 



135 



A 
K 


24- 




20- 




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1 
1 




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,1 
,1 




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4 7,4 14,2 E,lx 
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Figure 6 



136 



For an estimation of gallery illumination, we have to use samples from 
the total sum of illuminance in different points over the whole mine 
territory. 

As the standard prescribes a minimal level of illuminance, the task comes 
down to determining whether there is a probability for the random value of 
illuminance to be lower than the standard level: 



x — mm — / p dx 

X X 






Let m be the number of measurements and n - the number of results with values 
lower than the standard ones. 

Let us assume that the probability p for such a result can take a random 
value which satisfies the following condition: 

< p < 1 

After statistical data processing, it is possible to define the limits: 

PI < P < P2 » 
where the quantity p is located with probability of 

P m (pi - p £ p 2>' i * e - 
this is the confidence level : 

P m ( Pl £ P 1 P2> = p m ( P £ P2> " p m ( P £ Pl } . (2) 

After transformation we obtain: 

tiP r / «n N m! n , . >-m-n , _ N 

P m (n < N) = g n!(m . n)! P (1 " P) (3) 

n = 
or: P^ (p < Pl ) = 1 - P P +i ( n < N) = 1 - (l - Pl ) m+1 - (m + l) Pl (l - Pl ) m ... 

•" C m+1 Pl (1 " p l } (4) 



137 



If N = 0, we can use: 

p" =0 ( P <: P1 ) -.(■+!) fP 1 (l - P ) m dp = (i - p,) 11 * 1 (5) 



m 



< pi) = (m + 1) C V o l (1 - p) ra dp = (1 - P1 ) 




These expressions allow us to draw a number of conclusions concerning 
their validity made on the basis of a limited number of measurements. That is 
to say, they present the possibility of determining the number of the neces- 
sary measurements by giving the relative value of deviation p and the number 
of deviations from the standard n. 

For example: In a cycle of measurements are obtained: m = 49 with 

n = 9, which have a value lower than the standard one. Is the statement that 

the random number of deviation p is equal or less valid than 0,1 true? We put 
N = 9 and m = 50. 

P 49 ( P i °' 1) = 1 ~ P 5C) 1(N = 9) = 1 - 0,9906 = 0,0094 , 

where P ' (N = 10) = 0,9906 is taken from tables. 

We may investigate the opposite task. 

What should be the size of the sample m so that for one or another value 
of the deviation m we can state with a previously given truth that from the 
general sum total of which the sample is taken, the relative number of devia- 
tions (i.e. the probability of deviation at one-fold measurement) is not 
higher than the given p^ . It is clear that by decreasing p^ the number of 
measurements m should be increased. 

For example, from the data of the above example we have m = 50 and n = 10 
i.e. n/m = 0,2. We may state with confident probability 

P^ (P < Pi) = 0,0094 , 

that the real value p < pi only on the condition that 

Pl^ 0-1,5 n/m ~ 0,3. 

For practical purposes it is necessary to give the value of ~P\. If we accept 
that for a well-designed lighting installation all values obtained from the 
measurements of the luminance are higher than the minimum allowed level, then 
the decreasing of the luminance after a long-term exploitation is due mainly 
to the breaking down of a certain number of light sources. (it is assumed 
that a regular cleaning of the luminaires is done.) 



138 



If we accept that the light sources are changed when 10 percent get out 
of order we may determine the value of pj. 

For example, if the luminaires are located at a distance of 1 = 10 m 
between each other and if the broken light sources are evenly distributed, 
along 100 m in the gallery there will be at least one broken light source (or 
we may choose an area with at least one broken source) . The measurements are 
carried out at a distance of 1/2. It is clear that under the broken source we 
get luminance lower than the standard, i.e. N = 1. then p < 0,2 and at 

p n (p < pi) = 0,9 we get the number of the necessary measurements according to 
m 

formula (4). If N = 0, we get formula (5). 

As regards to the qualitative indices, assessment of the illumination is 
limited up to calculating the uniformity of the luminance and glare effect. 
It is expedient for calculating the uniformity to use expression 

E . 
min t , v 

gl-B (6) 

max 

The glare effect is calculated according to the classical methods. The 
measurements are carried out with a luxmetre ranging from 1-10-100 lx and an 
error of 10 percent , with a cosine correction of the photo receiver and 
corrected spectral sensitivity. 

The solution of the second problem; i.e., determining the reflection 
characteristics of the working surfaces in underground mines, is related to 
perfecting the design and control of the lighting equipment. The task is 
brought down to determining the reflection factor, P, of the light of various 
mine workings, building materials, mining machines, etc., so that the design 
could be carried out according to illuminance of the working surface and not 
according to luminance. This means that both the measuring and control of the 
light equipment will be done according to the same parameter; i.e., illumi- 
nance of the corresponding area. This is a very handy method and presents a 
lot of advantages as compared to the methods of measuring luminance. 

With the help of a laboratory photospectrometer , the reflection coef- 
ficients are measured at different frequences of the light for several types 
of coal and rock, as well as for different types of ore. The measurement of 
different building materials (concrete blocks, timber, etc.) is still going 
on. Measurements of the reflection factor of various mining machines are 
being prepared. When the measurements are completed, methods for design 
according to illuminance will be defined more exactly. 

The third problem — standardization of mine lighting — is quite topical. 
There are many differences between the recommended levels for one and the same 
working place in different countries. Apparently such great differences are 



139 



due to usage of different criteria and methods for determination of recom- 
mended illuminance. 

A common disadvantage of all used methods is the fact that for test 
objects are being used plane figures — transilluminated disks, rings of 
Landolt, written figures, etc. What are the disadvantages of these methods? 

1. The working surface is strictly fixed and the observer does not 
change the direction of his visual axis except in very narrow 
limits . 

2. The test objects are equally remote from the observer and, there- 
fore, the eye accommodation is not necessary. 

3. All test objects are with equal luminance and no eye adaptational 
processes are taking place. 

Some other disadvantages follow from ignoring the important processes 
accompanying the visual perception. For example, in neither of the experi- 
ments is it required to determine the form and size of the test objects — 
features which have great significance for the correct perception of the 
observed objects. 

All experiments are carried out in laboratory conditions. In this way, 
the disturbances, such as field noise, distribution of the attention, etc., 
are eliminated . 

How does the technological process proceed in the underground mines? 
Almost all operations in the mines — exploitation, loading, transportation, 
etc., are taking place in complicated circumstances — heavy traffic of machines 
and people; observation of the field operations, frequent change of the 
direction of the visual axis in which adaptation to different luminances is 
done. The presence of eye accommodation from near to far and vice versa 
should be particularly underlined. These two processes prolong the time of 
correct perception of the objects. 

Essential influence on the accuracy and rapidity of the reaction of the 
miners exert the perception of the sizes of the objects and treat them. 

According to the method and equipment described in detail in references 
2, 3, and 4, the investigation for standardization of mine lighting is carried 
out . 

As the most common criterion for visual performance capability the mean 
velocity of perception of visual information is taken: 

v - -|- , [-6JL.J (7) 



140 



where: H = pi log pi is the information capacity of the visual task; 
p. is the probability for recognizing any chosen feature; 
t, [s] is the time required for recognizing the test object. 

Eight stereometrical solids are selected as test objects — regular prism 
and pyramid (trihedral, tetrahedral, and hexahedral) , cone and cylinder. All 
solids are situated on the periphery of a circle with a diameter of 1,2 m. 
The visual task is to recognize three features of the test objects — shape, 
texture, and disposition of the test objects concerning the reference mark, 
situated in the centre . 

The quantity of information received by recognition of different features 
(one, two, or three) is calculated according to formula 7 and is shown in 
Table 1. 

TABLE 1 



No. 



1. 
2. 
3. 
4. 
5. 
6. 
7. 



Recognition features 



Shape, disposition, texture 

Shape, disposition 

Shape , texture 

Disposition, texture 

Shape 

Disposition 

Texture 



Probability, 
P 



1/32 

1/16 

1/16 

1/4 

1/8 

1/2 

1/2 



Visual informal 

tion capability 

H bit 



5 
4 
4 
1 
3 
1 
1 



While the investigations are being carried out, a reference mark appears 
in the visual field of the observer. At least one second after the appearance 
of the reference mark (that is, the time needed for the eye- accommodation of 
the observer), the test object appears. The time of recognition of the test 
object, from the moment of its appearance to the beginning of the observer's 
reaction, is measured. 



The measurements are carried out in field conditions at different illumi- 
nances. After statistical data processing of the obtained results, which 
express the relation V = f (E) , the level of illuminance will be determined in 
the interval with minimal value of the velocity of visual perception, V. 

The fourth problem on which considerable work has been done is creating 
appropriate mine-lighting equipment — luminaires, power-supply devices, safety 
devices, etc. It should be noted that because of the low profitableness, the 
production of explosion-proof luminaires is not being developed. The needs of 
this equipment are met through import from the USSR, Poland, Czechoslovakia, 
and DDR. 



141 



As a result of the expansion of mining production, a sharp need for 
lighting equipment is felt in the recent years. This fact called for the 
beginning of mine luminaire production. In the plan for mine-lighting 
research and development work, which goes up to 1985, the working out of 
luminaires for metal mines is planned to be carried out. For light sources 
are used fluorescent lamps and high-pressure mercury lamps . High-pressure 
sodium-lamps will be introduced in future. The development of floodlights and 
headlights for mining machines is also planned. 

The basic principles accepted for the development of mining luminaires 
are as follows: 

- The use of highly effective light sources — fluorescent lamps, high- 
pressure mercury, and sodium lamps. 

- Ensuring safe exploitation. 

- Ensuring long-term exploitation and high efficiency. 

- Ensuring maximum facilities for mounting and service. 

We shall consider some of the above-mentioned mine luminaire require- 
ments . 

The use of various light sources is determined mainly from the working 
condition and standard prescription for illumination of the working condition 
and standard prescription for illumination of the working places. Especially 
for transport and walking galleries, the workings in the stations, etc., with 
a height of not more than 2 to 2.5 m, most suitable are the fluorescent lamps 
since at high light efficiency they have considerably lower illuminance as 
compared with all the remaining light sources (5 to 8000 cd/m ) . 

The mine-lighting recommendations TC' - 4.10 demand that the illuminance 
of the emitting surface should not exceed 3000 cd/m 2 . It is obvious that we 
have to use fluorescent tubes with low wattage and apply diffusers with con- 
siderable area. These considerations are taken into account in the develop- 
ment of a luminaire intended for stationary lighting in underground metal 
mines. As a light source, two fluorescent lamps type White Light are used, 
each one having a power of 20W. 

As a construction the luminaire is designed in such a way that the 

starter switch ballasts are located on the side walls of the body. In this 

way the surface of the reflector is kept smooth and with regular concavity so 

that the multiple reflections of light are decreased and the efficiency of the 
luminaire is increased. 

At present, investigations for creating an optimal reflection surface are 
being carried out. The following requirements are necessary: 



142 



1. Formation of a pre-set light distribution curve. 

2. Ensuring high efficiency through avoiding multiple reflections of 
light in the luminaire . 

In order to prevent the harmful effect of mine waters and the mine atmos- 
phere, the luminaire body is made of plastic with high mechanical strength. 
Thus, the corrosive effect is eliminated and the weight of the luminaire is 
considerably decreased, which makes it safe and suitable for mounting and 
exploitation. 

In future, to facilitate the mounting, the input-output devices are 
planned to be designed with couplings. 

Light nets in the underground mines in Bulgaria are supplied by light 
transformers with a power supply of 2 to 4 KVA. It should be noted that 
according to The Safety Regulations in our country, a system with isolated 
neutral of the transformer is applied in underground mines. That is why the 
voltage is transformed from 380V (660V) to 220V (127V). 

All nets for voltage higher than 42V are equipped with devices for 
constant control of the isolation and earth-fault protection. 

For connecting the light net to the power supply, manual commutation 
apparatuses fitted with overcurrent protection are used. 

The basic co-ordinator and performer of the above-mentioned tasks is the 
Higher Institute of Mining and Geology in Sofia, the department of Electrifi- 
cation and Automation of Mine Production. In solving these problems the 
following subdivisions took part — the Ministry of Energy, the Ministry of 
Mineral Resources, the Ministry of Engineering Industry, and especially the 
Electrovacuum Factory in the town of Sliven and the Lighting Fitting Factory 
in the town of Stara Zagora. 



143 



REFERENCES 

1. Ganchev, G., Method for Estimating Underground Mine Lighting. IVth 
National Conference of Illumination with International Participation, 
Varna, 1978. 

2. Ganchev, G. , G. Anev , Method of Standardization of Mine Lighting. Illrd 
National Conference of Illumination with International Participation, 
Varna, 1978. 

3. Ganchev, G., On the Method of Standardization of the Illumination. 1st 
International Conference of Mine Lighting, Iashovec , 1978. 

4. Ganchev, G., Equipment for Mine Lighting Measurements. Symposium "100 
years of electrical illumination in Silesian collieries, Zabrze, 1980. 



144 



TITLE OF PAPER: Luminous Measurements in 

Firedamp Zones of Coal Mines 

AUTHOR: Dr.-Ing. Bruno Weis 

Messrs Adolf Schuck, K.G. 

Worms, Federal Republic of Germany 



Dr. Weis holds the position of Technical Manager, and for eight years 
has been responsible for the technical side of the company. He is a member 
of the TC-4.10 Mine Lighting Committee, and serves on Subcommittee SC-4.10A 
Mine Lighting Measurements. 



145 



LUMINOUS MEASUREMENTS IN FIREDAMP 
ZONES OF COAL MINES 

by 

Dr. Ing Bruno Weis 1 



ABSTRACT 

Mine lighting is of a great importance because of the fact that daylight 
is missing, that the degrees of reflection are low as well as due to the 
existence of large quantities of dust. 

Lighting is to provide good visual conditions; it has to create a pleas- 
ant visual environment and to influence positively the safety of work. 

The following expressions are good characteristics of lighting: 

Illuminance 

Uniformity 

Luminance limitation 

Direction of light and shade 

Light colour and colour rendition 

What can be measured are: 

Illuminance (horizontal, vertical, cylindrical) 

Luminance 

Degrees of reflection 

Screening angle 

Supply voltage 

Ambient temperature 

The measuring accuracy is dependent on the following parameters: 

Secondary normal 
V (A)-adjustment 
Room evaluation 

Linearity, dark burn, ambient temperature, frequency-dependence, 
etc. 

For this application the measuring instruments have to fulfill the 
following: 

Flameproof construction 

Large measuring range (e.g., 0,001 lx to 200.000 lx) 

Sturdy construction 



technical Manager, Messrs. Adolf Schuch K G, 
Worms am Rhein, West Germany 



146 

Battery operation (independent from the mains) 

Lightweight 

Small dimensions 

Simple handling 

Little temperature influence 

Storing the measured value 

In general, measurements are made because of the following reasons: 

A. New equipments are checked to find out if the requirements once 
specified are fulfilled; 

B. Equipments already in operation have to be checked in order to 
learn the actual condition. 

The measured values of the illuminance and of the luminance may be 
impaired by various factors affecting the use. In such a case an adjustment 
has to be made. 

As soon as the exact measured values are available, one must realize 
their presentation. 

The report of measured values to be made out must comprise all important 
parameters of influence. 

INTRODUCTION 

Mine lighting is of a great importance because of the fact that daylight 
is missing, that the degrees of reflection are low as well as due to the 
existence of large quantities of dust. 

Lighting is to provide good visual conditions; it has to create a 
pleasant visual environment and to influence positively the safety of work. 

Due to the aggravated environmental conditions and because of the fact 
that mine gas explosions might occur, it is not easy to measure luminous 
quality characteristics such as illuminance or luminance. For these reasons 
the luminous measurements cannot be made by means of standard devices but 
have to be carried out with mine-gas-proof ones. 

WHY ARE SUCH MEASUREMENTS MADE? 



It is intended to check at the place for instance luminous project plan- 
nings. Another reason which may be the most important one is the coverage of 
the actual condition of an existing lighting equipment for instance in a 
longwall or in the gob road. After such a measurement the measured values 
can be compared with existing standards and regulations. If it is found out 
that there is no coincidence, the equipment either has to be checked or re- 
paired; even a modification may be necessary. Another reason why such meas- 
urements of the luminous characteristics are made, may be the comparison of 



147 

various equipments with the aim. of. finding a useful solution as far as the 
luminous and the economic sides are concerned. 

QUANTITIES TO BE MEASURED 

As to mine lighting, the quantities to he measured are resulting from 
the requirements stated in the special regulations, that is to say from the 
characteristics of quality of the underground lighting. 

The most important quality characteristics are: 

Lighting level 

Distribution of light 

Limitation of glare 

Direction of light and shade 

Light temperature and colour rendition 

The most important quantities of luminous measurements are the illumi- 
nance and the luminance. The measurement of the degree of reflection can 
mostly be made outside the fiery zones. 

METHODS OF MEASUREMENT 

There are legal measurements and works measurements. Legal ones are 
generally carried out by test and surveillance authorities. They say that 
certain requirements with regard to the error limits of the measurements have 
to be fulfilled, to which further comments will be given later in this report. 

Works measurements mostly serve for finding out the instantaneous status 
of the equipment and for comparing such values with those specified in the 
standards and in the regulations. The result may influence in the one or the 
other way cleaning the lighting fixtures, exchanging the lamps or any re- 
equipment and enlargement of the existing lighting equipments. 

The measuring devices needed for the works measurements are subject to 
error limits that are considerably stronger than those of the legal measure- 
ments. 

CARRYING OUT THE MEASUREMENTS 



I have told you that there are two kinds of measurements. 

On the one hand there is the measurement of a new equipment and on the 
other hand you find out the actual working condition of a lighting equipment. 

It will hardly be possible to measure a new lighting equipment of a mine 
lighting system with the exception of a trial longwall and the like. 

If, however, a new equipment is measured, you should pay attention to 
the lamps and the lighting fittings to be cleaned. 



148 

If electric discharge lamps are used, the light sources should be at 
least 100 hours old and those of the incandescent lamps should have at least 
10 hours. 

The measurement shall take place only if a nearly stationary position has 
been reached. The same refers to works measurements. 

The daylight will by all means not be available. 

The measurements are to be carried out only if all equipments (machines, 
belt conveyors, longwalls and shield- type supports) have been installed. 

It is of an utmost importance - as far as low illuminances of mine 
lighting are concerned - to see to it that there is no shade on the light 
collecting area neither caused by the person making the measurement nor by 
the light reflecting from his clothes. Otherwise the measurement will not be 
correct. 

All measurements shall be made at ambient temperatures predominating 
during the operation. If this is not possible the ambient temperature of the 
lighting fittings has to be considered in the evaluation. 

Illuminances on roadways or certain distances are measured at a level of 
0,20 m above ground. 

When measuring a new equipment, in the beginning 1.25 (one and a 
quarter) of the nominal value are demanded. 

When measuring illuminances at working places or near machines, the 
relevant level always has to be determined and indicated. 

Also in this case the initial minimum value to be taken into considera- 
tion is 1.25 (one and a quarter) of the nominal value if the equipment is new. 
In case of a considerable contamination or of long maintenance intervals you 
should calculate with a planning factor of 1.43 to 1.67. 

At the latest if the illuminance has reached 60 percent, the lighting 
fixtures have to be cleaned and the lamps must be exchanged respectively. 

MEASURING DEVICES 

In this connection above all the technical report of the TC-2.2 of CIE 
must be mentioned: 

Methods of Characterizing the performance of Radiometers 
(Photometers, TC-2.2, Ninth Draft, March 1980.) 

Quantitative methods for the evaluation of the most important sources of 
errors of the photometers are described therein. For instance: 



149 
Systematic errors on the occasion of the calibration 

Differences between the ideal and the real spectral distribution of 
the sensitivity (f^) 

Errors of the spatial evaluation as to the illuminance (f2) 

Errors of linearity (f3) 

Fatigue (fs) 

Coefficient of temperature (fg) 

For rating the influence of the less important sources of errors, special 
methods are suggested. 

This concerns: 

Reading errors (fi+) 

Efforts in case of modulated radiation (f-j) 

Polarization effects (fs) 

Unequal sensitivity over the receiving zone (fg) etc. 

The admissiable total error should be equal 5 percent or smaller as 
regards legal measurements. 

It should be equal 20 percent or smaller as far as works measurements are 
concerned. 

It is recommended that the diameter of the sensitive area of the measur- 
ing head of the illuminance meter be - 3 cms. 

The most important luminous requirements an illuminance meter has to ful- 
fill with regard to mine lighting are: 

Sufficient sensitivity 

* V (A) loyal evaluation 

* for legal measurements f ^ < 1% 

* for works measurements f i < 6% 

* cos-loyal evaluation of the incident radiation 

* for legal measurements ti < 2% 

* for works measurements ±2 < 4% 



150 

The manufacturer recommends to recalibrate the illuminance meters regu- 
larly or at least every two years. 

This digital luxmeter is a high accuracy device for measuring the illu- 
minance and the mean luminance. It is particularly small and handy and has a 
3-1/2 digit display with five decadicly graded measuring ranges including 
autoranging system. The standard range reaches from 0.01 lx (last digit) to 
200 000 lx. Another version of this device has got a range from 0,001 lx to 
20,000 lx. 

The electrical and mechanical construction- of the device which is located 
inside a special steel housing, is good enough to fulfill the requirements of 
the mine-gas and of the explosion proof ness (Sch) i and (Ex) i. 

There is a luminance adapter which allows finding out even mean lumi- 
nances at working places and at space peripheries. 

This luxmeter is equipped witha 10 mm Si-photo-voltaic cell that is 
well adjusted to V (A) by full filtering. 

Moreover, the photovoltaic cell has got an integrated cos adaptor. Every 
device will be supplied with an individual test certificate for the V (A) 
adaptation and the cos gradient. 

The luminance adaptor has a flare angle of about 10 degres. When this 
accessory unit is used, the calibration of the device is automatically 
switched over to cd/m 2 . 

Furthermore the unit owns of switch for storing the measured value. 
There is a socket for remote controlling the value storage, thus avoiding the 
person in charge of the measurements to shade the measuring head. 

The built-in NiCd accumulator is suitable for an operation of about 10 
to 12 hours independent of the mains. 

Recharging the batteries is possible in non-hazardous locations at 220V 
or 110V (alternating voltage) by means of a plug/cable connection. Over- 
charging the accumulator is impossible due to the built-in automatic charging 
connection. The luxmeter has got a threaded tripod bush at the bottom side 
of the housing. The unit is proof against water jets and corresponds to IP 
54 ace. to DIN 40050. 

FURTHER TECHNICAL DATA : 

Resolution : 0.05% 

Absolute measuring error : - ± 0.5% ± 1 digit against PTB 

standards at vertical light radiation 
and standard illuminant A 



151 



Deviation of linearity 
Error of consistency 
Integration time 
Measuring rate 
Temperature coefficient 
Operating temperature 
Power consumption 



< 0.1% ± 1 digit 

< 0.1% ± 1 digit 
100 ms 

About 2 measurements / s 



cc < - 0.1% / C 



0° - 



+ 60°C 



< 500 mW 



Built-in battery testing equipment 
operating time with a fully charged 
battery 

Quick charge of the accumulators 

Mains connection 

Dimensions 

Weight 



ab. 10 to 12 hours 

ab. 6 to 8 hours 

220 V ± 10% 
110 V ± 10% 



or 



} 



50 - 
60 c/s. 



H x B x T - 

5.5 cm x 11.5 cm x 16.5 cm 

ab. 1.5 kgs. 



The absolute measuring accuracy that can be reached finally depends upon 
the uncertainty of the data of the secondary normal line being about 1.2%. 
Secondary normal lines are calibrated by national institutes. In general 
these are normals, normal receivers or the like which for instance are used 
for the calibration of measuring devices. 

EVALUATION AND STATEMENT OF MEASURING RESULTS 

The measured values of the illuminance and the luminance have to be con- 
verted to the agreed operating voltage of the mains. This conversion factor 
is given by the lamp manufacturer or can be learned from tables. 

The following is valid: Converted value = c x _N x measured value 

U 
c = convertion factor 

N = agreed operating voltage 

U = measured value of the mains voltage 

The measured results are booked either in tabular form or graphically 
for example in the ground plan of the longwall or of the section. 



152 

These measured values allow you to find out the following: 

A. Mean illuminance E 
v i n 

i = i x YZ E. 

i = number of the measuring point 

E. = illuminance at the measuring point i 



B. 


Minimum illuminance E . 

mm 


C. 


Maximum illuminance E 

max 


D. 


Uniformity g 

1 




g = e . / i 

1 mm 



E. Determination of A. to D. at the individual working place. 

The degree of reflection £ can mostly be found out outside the fiery zones. 

The results of a luminance measurement can be booked in tabular form or 
graphically as well. In this case, however, the exact observation place and 
the geometry of the space have to be indicated. 

Detailed investigations for the evaluation of the glare are not yet 
available. If, however, the experience from the emergency lighting is used 
(DIN 5035 section 5) , it will be sufficient to take the luminous intersities 
given by the manufacturer or to measure them and to compare them with the 
values of the DIN standards depending on the suspension height. 

Details of the colour temperature and of the characteristics of the 
colour rendition can be learned from the data sheets of the lamp manufacturers. 

The minutes of such measurements is to comprise the following informa- 
tion: 

A. The exact name of the mine and of the position of the longwall or 
of the section or the like. 

B. Names and addresses of the people who are responsible for the 
measurement s . 

C. Time at which the measurements have been carried out. 

D. All details such as type and type number of the measuring device 
used. 



153 



E. Ground plan, if available front elevation, of the space to be 
measured, of the area or of the working place; measuring screen is 
to be indicated. 

F. Exact data of the lamps and luminaires of the lighting equipment. 

G. Measured results. 
H. Room temperature. 

I. Particularities of the measurement. 

J. Comparison of the measured results and their discussion with what 
the DIN standards and their regulations demand. 

Information whether these requirements have been fulfilled. 

K. Signature, date. 



154 



TITLE OF PAPER: Reflectance Measurements 
in Mining 

AUTHOR: Mr. Donald Trotter 
McGill University 
Department of Mining and 

Metallurgical Engineering 
Montreal, Canada 



Mr. Trotter is an Associate Professor of Mining Engineering at McGill 
University. Prior to joining McGill, he had 20 years of practical experience 
in the mining industry in mine planning, mine production, and as mine manager, 
This work experience includes stints in Yellowknife, Bancroft, Sudbury, and 
Northern Manitoba. 

His present duties include teaching undergraduate students in mining 
engineering at McGill, as well as research and consulting in mining methods 
and mine safety. 

He is a member of the Canadian National Committee of the International 
Commission on Illumination and chairman of the Subcommittee on Mine Light 
Sources of Technical Committee 4.10 Mine Lighting of the Commission Inter- 
nationale de l'Eclairage. 



155 
REFLECTANCE MEASUREMENTS IN MINING 

by 

Donald Trotter 1 

ABSTRACT 



Regulations and guidelines for mine lighting can be expressed either in 
terms of illuminance or luminance. Since luminance relates to what the eye 
actually sees, this is becoming the preferred method. Unfortunately, however, 
it is the more difficult of the two concepts to work with. The illuminance 
put out by a source is known from the manufacturer's isolux and isocandela 
diagrams and luminance can be calculated if the surface reflectance is known. 
Accurate measurements of reflectance then provide the missing link for good 
lighting design. Measuring methods for reflectance are described and results 
of measurements on selected working longwall faces are presented. 



INTRODUCTION 



The International Commission on Illumination (CLE.) is an organization 
of 29 countries devoted to international co-operation on all matters relating 
to the art and science of lighting. One of its objectives is to provide guid- 
ance in the application of the basic principles and procedures to the develop- 
ment of international and national standards in the field of lighting. This 
work is carried on by 26 Technical Committees, each of which is assigned to a 
member country. The reports and guides developed by these international com- 
mittees are possible only through an organization such as the CLE. and are 
accepted throughout the world. 

Technical Committee 4.10 of the CLE. is involved solely with mine 
lighting with delegates appointed from 19 of the member countries. At the 
last annual meeting of this committee, held in Katowice, Poland in April 1980 
several important decisions were made on the preferred method of specifying 
mine lighting standards for underground coal mines. These standards are not 
binding on the member countries but act as important guidelines for the var- 
ious countries as they struggle to establish their own individual standards. 

The following is a summary of the more important guidelines. 

1. Luminance levels should be specified rather than illuminance levels. 

2. Minimum luminance is dependent on the nature of the task and the working 
conditions. 

1 Associate Professor, McGill University, Montreal Canada, Department of 
Mining and Metallurgical Engineering 



156 



(a) where traffic is light and mechanization is minimal but 



general lighting is desirable because of safety 
considerations 0,05 cd-m 



-2 



(b) where mechanized equipment normally 

operates 0,2 cd'm 



(c) underground chambers where precision work 
is not performed 10 cd*m 

(d) underground chambers where precision work 
is being carried out 20 cd-m 



-2 



-2 



3. The luminance in the visual field of a miner should not change more than 
five times in a distance of 1 m, measured along the area being observed, 
provided that the reflectance in this observed area does not change 
either. In other areas the uniformity of luminance should be no more 
than 10:1. 

4. Values under 3000 cd« m in a miner's visual field are acceptable as a 
permissible luminance of light sources used for network illumination. 
In headings and other workings, luminaires giving values greater than 
3000 cd'tn can be used provided they are placed above the line of 
vision. In horizontal workings this is taken as a minimum height of 
2,5 m from the floor to the centre-line of the source. 

PRESENT WORLD PRACTISE 



No two countries seem to be. able to agree on how to specify mine light- 
ing standards for coal mines but they can be lumped into four distinct groups. 

GROUP 1 - Countries which specify minimum standards of illuminance based on 
the location in the mine, e.g. Belgium, Czechoslovakia, Federal Republic 
of Germany, Hungary, Poland. 

GROUP 2 - Countries which do not specify minimum standards of illuminance 

but publish recommended minimum values of illuminance as suggestions for 
the mining industry, e.g. United Kingdom. 

GROUP 3 - Countries which specify neither minimum standards nor recommended 
values. Where lighting is required it must be 'sufficient' or 'suitable* 
e.g. Australia, Canada. 

GROUP 4 - Countries which specify minimum standards of luminance based on 
the location in the mine, similar to the recommended guidelines of the 
CLE. e.g. United States. 



157 



PRESENT U.S. PRACTISE 



The United States is the only country which can be placed in Group 4 at 
the time of writing (Oct. 81) and it has the most stringent mine lighting 
standards of any country. The standards have been the subject of many papers 
(3,5,9) and will not be dealt with other than to mention that three important 
concepts were recognized. 

(1) Luminance was to be used as the measuring criteria. Theoretically this 
allows flexibility in design to take into account the variation in reflectance 
found in the real world. 

(2) The standards required much more than task lighting. Peripheral vision 
was thus recognized as being important for the safety of miners. 

(3) The maintenance of a minimum level of luminance ensures that adaptation 
problems will not be severe. 

In practise, however, the reflectance is not measured for each install- 
ation. The illuminance of the light sources are evaluated from photometric 
data obtained in an illumination laboratory of an equipment manufacturer or 
in the illumination laboratory here at Beckley. The luminance is then cal- 
culated by assuming a coal reflectance of 0,04 and also assuming a planning 
factor of 1,3. There is a built in danger to this method in terms of excess 
cost and harmful glare if the assumed reflectance is much less than the actual 
reflectance. As well, manufacturers tended to over-design so that their 
equipment would be in compliance in any mining situation. As a matter of fact, 
assumed reflectance was previously lower than 0,04 but was raised to its pre- 
sent value largely to help alleviate operator complaints about glare. 

-2 
The U.S. standard converts to 0,2 cd-m in SI units. This is the value 

recommended by the CLE. to be the minimum luminance level where mechanized 

equipment normally operates. Comparisons with Group 1 countries are difficult 

since standards are stated in illuminance rather than luminance. Assuming a 

diffuse reflectance of 0,05, then an illuminance of 15 lx would produce a 

luminance of around 0,2 cd*m . Values around 15 lx occur in the standards 

of several countries so there appears to be general world-wide agreement on 

the required lighting levels. 



REFLECTANCE THEORY 



Good underground lighting design is not possible without a knowledge 
of reflectance. Not only do we see by reflected light but in an underground 
mine that portion of reflected light which does enter the eye is usually only 
a small percentage of the light that struck the object being observed. The 
majority of the light is absorbed by the surface. Measurements of this 



158 



phenomena are required so that the lighting installation can compensate for 
the loss or the surface can be modified to cut down on absorption. 



Reflectance (p) can be thought of as a measure of the efficiency of a 
surface in retransmitting light. If p = 1,00 then the surface reflects all 
the light and if p ■=, 0,00 all the light is absorbed. Natural surfaces have 
reflectances somewhere between these extremes. In practice nearly all sur- 
faces are a combination of diffuse and specular reflection. Reflectance can 
then vary over a considerable range of values or stay fairly constant for the 
same material. If reflectance stays constant, surfaces appear equally bright 
when viewed from any direction. For most surfaces, brightness is greater when 
the viewing angle is close to the angle of incidence. Various types of re- 
flectance are illustrated in Figure 1 with the arrows having a vector connota- 
tion. The top left diagram illustrates specular reflectance and is the type 
one obtains from a shiny metal surface or a mirror surface. The top right 
diagram shows specular diffuse reflectance where most of the light is reflec- 
ted specularly but there is a slight diffuse component. Gloss and semigloss 
paints reflect light in this manner. Diffuse specular reflectance is 
illustrated in the lower left diagram and completely diffuse reflectance in 
the lower right diagram. In a dry mine, most surfaces exhibit diffuse specu- 
lar reflectance but a very dusty or powdery surface would come close to 
exhibiting completely diffuse reflectance. 







FIGURE 1. - Types of reflectance 



159 



The figures shown are an oversimplification of what actually takes place 
since only one ray of incident light is shown. A cone of light could strike 
the surface, or the incident light could be arriving from all directions. Sim- 
ilarly, one could attempt to measure the reflected light in only one direction, 
could measure a bundle of the reflected rays of light, or could measure all of 
the reflected light. This means there are three geometrical conditions for 
both the incident and collected fluxes: hemispherical, conical and direct- 
ional. Using the various combinations it is possible to have nine kinds of 
reflectance measurements: (1) bi-hemispherical; (2) hemispherical-conical; 
(3) hemispherical-directional; (4) conical-hemispherical; (5) bi-conical; 
(6) conical-directional; (7) directional-hemispherical; (8) directional- 
conical; (9) bi-directional. Angles of incidence and of recording as well 
as the solid angles should be specified if accurate reflectance measurements 
are being made. 

The incident angle is specified first, and then the recording angle. 
When the solid aneles are not specified the assumption is made that they 
are infinitesimal which means the reflectance would not change if they were 
made smaller. With textured surfaces the orientation of the surface may be 
important. A ribbed surface may have different reflectances depending on 
whether the incident light strikes it along the axis of the ribs or at right 
angles to the ribs. Similarly a flat surface can give different reflectances 
depending on the angle at which it is tilted. It is important to measure this 
tilt angle when the incident and recorded light path and the normal to the sur- 
face do not all lie in the same plane. It may also be important to specify 
the type of light that strikes the surface. When all other parameters are 
held constant, reflectance varies with the illuminating wavelength. 

UNDERGROUND REFLECTANCE MEASUREMENTS 



Four different techniques have been employed by McGill University 
researchers. These are: 

(1) reflected-incident light comparison 

(2) standard chips comparison 

(3) reflectance standard comparison 

(4) sphere ref lectometry 

The first technique is the easiest but is the least accurate. The second 
method gives an approximate reflectance value which is usually sufficient 
for design work. The third method is tedious but more accurate. The 
fourth method is the most accurate but requires special equipment. 



160 



(1) Ref lected-Incident Light Comparison 

The method is useful in determining the reflectance of diffuse surfaces. 
A small box-shaped lux meter is placed against the surface to be measured and 
then drawn back about 0,1 m to avoid shadows. A reading of the illuminance 
given off by the surface is recorded. The meter is then turned around and 
held against the surface and a reading of the illuminance is recorded. When 
this type of lux meter is used, the meter dial should face up to prevent any 
error that might result from unbalance of the microammeter . The reflectance 
p can be determined from 

p - !l 

E 2 

where p = reflectance 

E 1 = illuminance emitted from surface whose reflectance is 
required 

E~ = illuminance striking the surface under test 

Some problems arise with the method. If the same lux meter measured the light 
reflected from a surface and is then turned around to measure the illuminance 
from a source, it has to be assumed that the reflectance is completely diffuse. 
Although the operator is careful that shadows do not fall on the face of the 
cell, he is blocking light which would otherwise reach the surface, so that 
instrument accuracy may suffer. 

(2) Standard Chips Comparison 

A very simple method is available to determine the approximate reflectance 
of a surf ace (8). Chips of various known reflectances can be purchased from the 
Munsell Color Company or can be made up from commonly encountered surfaces. 
After the sample is selected whose reflectance is required, the chip that ap- 
pears closest in brightness to the sample is compared to the sample surface, 
being careful to mask out surrounding surfaces. For most accurate results, the 
mask should have a reflectance close to that of the unknown surface. The neu- 
tral matte chips are arranged in the following pattern of reflectance (Figure 
2). 

0,025 0,031 0,038 0,046 0,055 0,066 
0,066 0,077 0,090 0,104 0,120 0,137 

The chips do not increment uniformly in reflectance but are designed so 
that the changes in greyness appear to the eye to occur in uniform steps. The 
0,066 chip is repeated in the second row to facilitate easy matching. Figure 2 
shows a match being attempted for a surface with a reflectance close to 0,012. 



161 



Standard Chip 



□ □ □ 

0,046 0,055 0,066 


DI 


A V 




[S 






Dl 


^ T 


DI 


Dl 




tfi 


Di- 




0,025 


Df 





Mask 



Test Sample 



FIGURE 2. - Reflectance by chip comparison 

An estimate can be made of the reflectance of the sample by comparing it 
to the known reflectance values of the two chips that appear closest in bright- 
ness, The mask is large enough that the two chips and the surface can all be 
compared at the same time. 

It is important that the comparison method be done using the same type of 
light source that will be installed in the working place. For example, the re- 
flectance of a yellow rock surface will be higher under sodium light than it 
will under an incandescent light. Strongly coloured rocks or other surfaces 
show the greatest changes in reflectance with different source types. For neu- 
tral greys, there is little change in reflectance using different types of 
lights. 

(3) Reflectance Standard Comparison 



This method is more accurate but takes more time. When possible, spec- 
imens can be gathered so that reflectance measurements can be performed in a 
laboratory where conditions are more accurately controlled. When it is not 
possible to remove a test surface or when it is felt that by removing the sur- 
face the light properties would be modified, measurements are conducted in the 
field. The measurement of reflectance in a mine is often difficult because 



162 

of time limitations and the variety of surface structures and conditions. 
Hence, it is not possible to make complete measurements with the same accuracy 
as in the laboratory. For these reasons, field reflectance values are approx- 
imations obtained using abbreviated measurement techniques. When the light 
source can be controlled, a miner's cap lamp mounted on a tripod serves as the 
source, and a common cap lamp battery is the power supply. Lumen depreciation 
due to battery fatigue can be checked with a suitable meter. The light source 
is positioned so as to give a 45 incident angle on the test sample surface 
(Figure 3) . The ratio of the luminance of the test sample surface to the 
luminance of a known surface is used to determine test sample reflectance. 
Typically on an unlit longwall face the photometer is held about 1,5 m from 
the coal face and the operator is underneath the chocks. A source held about 
0,7 m from the coal face at the edge of the chocks provides sufficient lumi- 
nance for readings to be taken. 



Surlace to 
"Be Tested 



\ 



-i? 



s 

\ 



* — Photometer 



V 



■Source 



FIGURE 3. - Geometry for reflectance standard comparison 

Luminance measurements are made on the surface to be tested and on a standard 
surface of known reflectance which is mounted on top of the surface under 
test. The reflectance of the surface under test is 

P = P L 
s 



L 
s 



where 



P - reflectance of surface to be tested 

p = reflectance of standard surface 

s 

L = luminance of surface to be tested 

L - luminance measured off standard surface 
s 



163 

CIE standard conditions for reflectance measurements state "for the 
illuminator, illumination shall be within five degrees of, and centred about, 
a direction of 45 degrees from the perpendicular to the test surface. The 
area of the illuminated spot should be not less than that of a circle seven 
centimeters in diameter. Viewing should be within ±5 degrees of, and centred 
about the perpendicular". The basic reference standard for 45-degree, 0- 
degree reflectance measurements using CIE standard conditions is a pressed 
layer of freshly prepared magnesium oxide. It is assigned a reflectance of 
1,00 for the conditions of 45-degree illuminance and perpendicular view. It 
is not convenient to use this standard underground because of preparation time 
and the large number that are required. Since the mine atmosphere is usually 
dusty, fresh standards should be used for each reading. Fortunately second- 
ary standards can be calibrated relative to the reference standard. 

Various secondary standards can be used. Porcelain-enameled metal 
plaques are reasonably permanent in reflectance and uniform over the surface. 
Hitchcock(5) , in his work on reflectance in underground coal mines, used 
"Millipore" Filter Paper #29325. This paper approached a lambertian surface 
and has been compared to a magnesium oxide surface for every possible geom- 
etric condition of the ref lectometer . Its only drawback is cost. Munsell 
Color Company sell a set of 32 chips ranging in reflectance from 0,025 to 
0,900. Individual sheets can be purchased so that a secondary standard can 
be obtained which is close to the material to be measured. A good secondary 
standard is a Kodak Neutral Test Card Cat. 1527795, designed primarily for 
colour photography. The card is about 200 mm x 250 in size, and has a grey 
side of 0,179 reflectance and a white side of 0,900 reflectance in the 45°/0° 
position. The grey side in particular is useful in mine work because of its 
low cost, its guaranteed uniformity from card to card, its thickness which 
allows easy mounting, and because its reflectance often closely approximates 
that of underground surfaces. This latter feature is important since bright- 
ness matches can be made quickly when using visual photometry methods. 

In practise the cards can be cut into four and individually placed in 
plastic bags sealed with tape to protect them from moisture and dust. Cards 
are fastened onto the surface to be measured by placing caulking compound from 
a gun and cartridge onto the white side and pressing the card firmly into 
place. Cards are normally destroyed after one use, since humidity, dust or 
dirt might affect their light reflecting properties. 

Measurements are made to determine reflectances of various mine surfaces 
with the photometer either hand-held or tripod mounted. The observer must be 
close enough to keep the object completely in the viewer. The record angle, 
which is between the axis of the telescope and an axis vertical to the test 
plate, and the incident angle, which is between the axis vertical to the test 
plate and the light source, should be recorded. On structured surfaces the 
tilt angle, which is between the plane of the surface being measured and the 
plane formed by the incident beam and the recording line of sight is also meas- 
ured. The method assumes diffuse reflectance and surfaces should appear dif- 
fuse to the eye. Table 1 shows field measurements taken from coal mines in the 
Sydney area of Nova Scotia in Canada using a J-15 photometer [MSA 39762] (3). 



164 



CO 

c 
o 

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•2 c 

15 


Readings every 10 chocks from 
#10. Rough walls. Bedding not 
visible. Clean, very dry coal 
surface. 


Readings at chocks 5,12,16 and 
every 10 to #126. Clean, dry 
smooth coal surface. -Bedding 
well defined. Lights 4th chocks. 


Readings every 10 chocks from 
#7 to #127. Varied wet and 
dry. Varied clean, dusty and 
very dusty. 


Readings every 10 chocks from 
#15 to 45 plus 53 and 56. 
Rough face, bedding not 
visible, dusty, wet. 


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165 



(4) Sphere Ref lectometry 



Sphere reflectometry provides a method of taking bi-hemispherical reflec- 
tance measurements. In this technique, all flux reflected in 2ir steradians is 
included in the measurement, using a device called a sphere ref lectometer. This 
is a receptor which is an integrating sphere having a flat circular aperture and 
is placed over the surface to be measured. Normal mine lighting design practise 
does not require such a refined technique. 

LABORATORY GONIOREFLECTANCE MEASUREMENTS 

The reflectance standard comparison method can be used in a photometric 
laboratory to measure how the reflectance of different surfaces varies with 
the incident angle and the viewing angle for bi-directional conditions. Since 
there is an infinite number of geometric conditions, incident angle is usually 
held to . Zero degree incidence is the most important angle since a cap 
lamp, headlights on a jumbo, etc. are generally shone directly rather than 
obliquely onto the surface to be viewed. 



Incident Angle 
Goniometer 

Test Surface 



Optical Bench 




FIGURE 4. - Plan view of bi-directional reflectance measurement 



166 

The position of the detector is located with respect to the light 
source. This location is defined by the OFF ANGLE which signifies the 
angle between the detector and the light source, and the READ ANGLE which 
denotes the polar position of the detector around the light beam, with the 
position corresponding to the zenith. Azimuth angles are then read as 
one faces the specimen under study. With test surfaces mounted on the 
goniometer the beam of incident light could be moved through a horizontal 
plane perpendicular to the surface measured. This is the INCIDENT ANGLE. 
The specimen could also be rotated about a vertical plane, and is recorded 
as the TILT ANGLE. When measuring a non-ordered surface, the tilt becomes 
meaningless and is not recorded. The complete geometry of a bi-directional 
reflectance measurement, as illustrated in Figure 4, includes (1) incident 
angle, (2) off angle, (3) read angle, (4) tilt angle, and (5) colour tem- 
perature. Figure 5 summarizes the results of many hours of laboratory exper- 
iments to determine reflectances of substances. Materials plotted to the 
left of the chart tend to soak up light, while those occurring to the right 
are more easily seen since not too much light is trapped. The longer the 
length of the bar, the more specular the surface tends to be or the more 
varied the results are from different samples of the same substance. A 
comparison of the reflectance values for coal and magnesite will help the 
reader to appreciate why it is infinitely easier to light the working face 
of a magnetite mine. 



Clean Cement 



R*tlecli«T»pe 



Old Ctmant 



Clean Srotcrete 
F»d»d Whitewash 



Fresn While Wasn 



S-wn-"imber 



PlaVx (VHio.v Lame Osh.) 



S;alc 



Cat. Slllston* 



Serpentine 



Biolin ScSiit 



Qur'tj Diorite 



Chlorite Sen *l 



£& 



OxxJiKd Cha'rooy r ile 



P«nt«-yrr1o(Oiid.le:)) 



_ 



Frts* OolcoryHe 



FIGURE 5. - Reflectance 



167 

LUMINANCE CALCULATIONS 

The illuminance distribution of a luminaire is obtainable from the manu- 
facturer. One should verify, however, that the values have been obtained by 
a well-known independent testing laboratory. The reflectance can be deter- 
mined by methods outlined in the previous section. Expected luminance values 
can then be calculated. 

L _ £L_ 



-2 
where L - luminance in cd-m 

P = reflectance (dimensionless) 

E r illuminance in lux 

Luminance takes into account the light which actually leaves a surface 
and consequently gives us the subjective sensation of brightness and contrast. 

When a lamp is used to light a mine opening, the light falling on the 
floor, walls, and ceilings causes these surfaces to act as light sources, but 
only a portion of the light gets reflected. This light, on striking floor, 
walls and ceilings, allows a portion to be re-reflected and the process of 
inter-reflections continues ad infinitum. The net effect could be that the 
total number of lumens projected from the rock surfaces could exceed the lumens 
put out by the source. This condition is quite common in confined spaces with 
high reflectances. 

If the uniform reflectance of the rock surfaces is P an< ^ a luminaire is 
giving of $ lumens, then the number of lumens being emitted from the rock sur- 
faces is given by $p (1+ p + p * . . . f p 00 ). 

2 -1 

Since p < 1, the series 1 + p + p t ... can be summed and equals (1 - p) 

The total lumens emitted from rock surfaces is then given by $p/l - p 

To illustrate, if the reflectance was 0.2, then total lumens would be 
0,2$/0.8 =s 0,25 $. Although this is not much of an increase, notice what 
happens for higher values of p. 

For a reflectance of 0,6, total lumens becomes 0,6$/0,4 = 1,5$. 

The theory shows that by changing rock reflectance from 0,2 to 0,6 (a 
factor of 3), the available light alters by a factor of 6. 

In practise, measured results are less than this, as some of the light 
gets absorbed by the atmosphere and the area being lit is not completely en- 
closed, causing some light to escape through the openings. Nevertheless, the 
theory illustrates the value of treating mine surfaces of low reflectance to 
get much greater benefit from the available light. 

The theory also shows that for mine surfaces with reflectances below 



168 



about 0,2 then the added benefit of light achieved by inter-reflections is 
not enough to affect calculations. Above 0,2, the designer may want to take 
into account the additional light available due to inter-reflections. 

The luminance falling at a point on the floor can be expressed as 



cos 9 » p 



Ab 



h 2 ' 7T ' (1-p) 



where I = the intensity in candelas from the source to the point of 
measurement 

= the angle between the vertical and a line from the source 
to the point of measurement. 

p = reflectance 



Ab = absorption factor 

h = the mounting height in metres 



Where rock reflectances are low, the Ab term and the (1-p) term will be 
very close to each other and to all intents and purposes will cancel each 
other out. The formula can then be simplified to 




Similar formulas can be used to determine wall luminance or back lumin- 
ance and are extremely useful in determining lamp spacing. For practical 
reasons, lamps should be spaced far apart to keep capital costs down, but 
the level of luminance should not fall below some predetermined value estab- 
lished in a standard or in a guideline. The formula is also useful in deter- 
mining the uniformity of luminance between lamps to make sure that hot spots 
do not occur. 



169 
SOME OBSERVATIONS 



These observations are based on underground reflectance measurements 
of coal classified as volatile class A bituminous at three mines in the 
Sydney-Glace Bay area of Nova Scotia, and on laboratory studies of several 
selected samples of coal taken from two working seams at these mines. 

- Based on bi-directional 45°/0° underground measurements, the 0,04 design 
value for coal reflectance currently in vogue in the U.S.A. is a good 
design value (Table 1) . 

- Laboratory measurements of reflectance tend to be lower than field 
measurements for the same bi-directional geometry. 

- Measurements on dry longwall faces exhibit a smaller standard deviation 
than wet longwall faces on the same seam. 

- Longwall faces dry rapidly after the passage of the shearer drum. 

- Gonioref lectance measurements in the laboratory display a high standard 
deviation for both dry and wet samples (Table 2) . Lowest recorded value 
was 0,011 and highest was 0,16. 

- Highest gonioreflectance readings are obtained when the viewing angle is 
close to normal to the coal face i.e. coal exhibits specular diffuse 
reflectance. 

- Hemispherical-conical reflectance measurements exhibit a low standard of 
deviation as the viewing angle is changed. 



170 



CONCLUSION 



Very little information is available in the literature on reflectance 
measurements in coal mines. If luminance is to be the governing criteria for 
standards and guidelines, then more research is required into the reflectance 
of underground coal seams. The 0,04 reflectance value so commonly employed is 
certainly a good design value for many situations but could be a poor choice 
for many other situations. 

Lord Kelvin expressed the problem in these words: "When you can measure 
what you are speaking about, you know something about it. When you cannot 
express it in numbers, your knowledge is of a meagre unsatisfactory kind; 
although you may have the beginnings of knowledge, you have scarcely in your 
thoughts advanced to the stage of a science". 



Since the CIE has stipulated that luminance is the preferred method, a 
uniform method of measuring reflectance is required. The method should be 
simple and relate to the real world. One suggestion is to use hemispherical- 
directional reflectance measurements, that the direction be at right angles 
to the coal face, and that the acceptance angle of the photometer be set be- 
tween about 10 degrees and 15 degrees. This would most closely duplicate a 
longwall face illuminated with an almost continuous string of intrinsically 
safe luminaires, which is fast becoming the most common method of coal mining 
throughout the world (Figure 6) . 



Chocks 




onveyor 



Powe 



FIGURE 6. - Method of lighting a longwall face 



171 

A common reporting method for the lighting situation depicted would allow 
comparisons to be made among coal seams throughout the world, perhaps leading 
to a classification system of coal seams for luminaire design. 



REFERENCES 

1. CROOKS, W.H. 'Definition of Safety Illumination Needs for Underground 
Metal and Nonmetal Mines' 50th Annual Technical Sessions of the Mines 
Accident Prevention Association of Ontario, Toronto, Canada, May 1981 

2. EDITORS 'IES Approved Method of Ref lectometry' Journal of the Illumin- 
ating Engineering Society, 3, 168, 1974 

3. FEDERAL REGISTER. 'Underground Coal Mines: Illumination Systems, Pro- 
mulgation Date and Testing and Evaluation Procedures'. Department of 
the Interior. April 1, 1976 

4. HALLDANE, John F. , 'Guidelines for Mine Lighting' Institute for 
Applied Technology, National Bureau of Standards. Oct. 1970 

5. HITCHCOCK, Lyman C, 'Development of Minimum Luminance Requirements 
for Underground Coal Mining Tasks' . Research and Development Department, 
Naval Ammunition Depot. Jan. 1973 

6. KEITZ, J.A.E., 'Light Calculations and Measurements' Macmillan, 1971 

7. LASALLE, E. 'Reflectance Measurements on Canadian Coal Seams' 
Unpublished M.Eng. thesis, McGill University, 1981 

8. MACBETH, N. 'Munsell Value Scales for Judging Reflectance* Illumin- 
ating Engineering, 44, 102, February 1949 

9. PATTS, Larry D. , 'Practical Compliance Problems with the New Mine 
Lighting Law - Coal'. SME-AIME Preprint Number 77-F-41. 1977 

10. ROBERTS, A. 'Mine Lighting - Value of Reflectivity' Iron and Coal 
Trades Review, 1957 

11. ROINES, G. and LEE, K. 'In Situ Rock Reflectance' Photogrometric 
Engineering and Remote Sensing, Vol.41, No. 2, 189, 1975 

12. SHARPLEY, F.W. 'The Direct Reflection Factor of Coal' Proc. S. 
Wales Inst, of Engineers, 40, 158, 1939 

13. TAYLOR, A.H. 'Errors in Ref lectometry' Journal of the Optical 
Society of America, Vol.25, No. 2, February 1935 



172 



TITLE OF PAPER: Visual Attention Locations 

and a Methodology for Assess- 
ing Visibility from Underground 
Mining Equipment 

AUTHOR: Mark S. Sanders, Ph.D. 

Canyon Research Group, Inc. 
Westlake Village, California 



Dr. Sanders received his Ph.D. Degree from Purdue University, and is 
Professor of Psychology, California State University, Northridge. He is 
a Senior Staff Scientist at Canyon Research Group, and has published 
numerous technical reports and journal articles on haman factors, with 
emphasis on applications in mining. He is also co-author of Human Factors 
in Engineering and Design , 5th Edition, McGraw Hill, 1982. Dr. Sanders is 
a member of the Human Factors Society, American Psychological Association, 
Ergonomics Society, and Society of Automotive Engineers. 



CO-AUTHORS: James Peay 

Technical Project Officer 
U.S. Bureau of Mines 



Thomas Bobick 

Technical Project Officer 

Pittsburgh Mining & Safety Research Center 

Pittsburgh, Pennsylvania 



173 



VISUAL ATTENTION LOCATIONS AND A METHODOLOGY FOR 
ASSESSING VISIBILITY FROM UNDERGROUND MINING EQUIPMENT 

by 

Mark S. Sanders, Ph. D. , James Peay, and Thomas Bobick' 



ABSTRACT 

A task analytic approach was used to define information requirements and 
visual features which served as sources of information for operations of con- 
tinuous miners, shuttle cars and scoops. Information requirements were prior- 
itized and the location of visual features determined. From this analysis, 
visual attention locations, containing one or more important visual features, 
were identified. A total of 74, 54, and 54 visual attention locations were 
developed for continuous miners, shuttle cars and scoops respectively. 

A procedure was developed for assessing whether operators in existing 
machines could be expected to see the visual attention locations. The proce- 
dure makes use of a Human Eye Reference Measurement Instrument (HERMI) design- 
ed for this project and an outside-in-photographic procedure. A sample of 
continuous miners, shuttle cars and scoops were used to test the procedure. 
Illustrative results are presented. 

INTRODUCTION 

This research was carried out under Contract J0387213 awarded to Canyon 
Research Group, Inc., by the Bureau of Mines, Pittsburgh Research Center, 
Bruceton, PA. The primary purpose of this effort was to determine the visi- 
bility requirements for shuttle car and continuous miner operators. Scoops 
were considered, insofar as they fulfill functions in the mine similar to 
those carried out by shuttle cars (i.e., loading, transporting, and unloading 
of coal). A secondary objective was to evaluate the actual field of visibil- 
ity for a sample of machines. The purpose of this latter evaluation was to 
develop a simple procedure for visibility evaluation of mobile equipment. 

DETERMINING WHAT NEEDS TO BE SEEN 

It is important to distinguish visibility requirements ; i.e., what 
needs to be seen, from fields of visibility ; i.e., what can be seen. Deter- 
mining what operators need to see in order to perform their job efficiently 
and safely can only be determined by observing operators performing the task 
and by interviewing them. Fields of visibility, on the other hand, can be 
assessed objectively and independent of the operator by recording what actu- 
ally can be seen from the operator's position. 

1 Senior Staff Scientist, Canyon Research Group, Inc., Westlake Village, CA 
2 Technical Project Officer 
Technical Project Officer, Pittsburgh Mining & Safety Research Center 
Pittsburgh, PA 



174 



The observation and interview approach was used in this project to deter- 
mine what needs to be seen while operating equipment. A total of twelve mines 
were visited. A total of 28 working sections were observed and approximately 
100 operators interviewed. Operators with varied degrees of experience were 
interviewed. No systematic differences in visual requirements were noted be- 
tween novice and experienced operators. 

A problem typically encountered in determining visibility requirements 
was evident in the operators' responses. When asked what they needed to see, 
most operators responded in terms of what they could see. The logic being 
that they do their job effectively and safely and if they cannot see a partic- 
ular feature, therefore, it is not necessary to see it. This problem was 
somewhat overcome by using a task analytic approach in the interviews. 

Using a task analytic approach, the job was divided into tasks, e.g., 
loading, tramming, unloading. For each task, the operator was asked what in- 
formation is required to do the job, e.g., position of shuttle car relative to 
the tail boom of the continuous miner, location of obstacles in the roadway, 
position of shuttle car in roadway; information requirements being global in 
nature. For each information requirement, specific visual features which 
serve as sources of that information were then identified. 

The importance of each visual feature was determined by rating the im- 
portance of each information requirement in terms of safety and productivity. 
The location of each visual feature in the visual field was determined. From 
this information, visual attention locations, where one or more visual fea- 
tures are located, were identified. 

The two unique features of this approach are the pivotal function played 
by information requirements, and the system for specifying the location of the 
visual features and visual attention locations. 

Information requirements are broad categories of information that the 
equipment operator needs in order to operate the equipment safely and effi- 
ciently. The types of information that are relevant to our purposes are those 
that relate to the interface between the machine and the mine environment. We 
are not concerned with the stored knowledge required to operate the equipment 
such as the function of the various controls on the machine. We are concerned 
with information that changes as a function of time or location within the 
mine and for which the visual sense is a significant source. 

There are usually multiple sources of information available to satisfy 
any given information requirement. In some cases, redundant sources exist, in 
other cases, several individual sources must be combined in order to satisfy 
the requirement. Not all sources of information are visual; some are auditory 
and others are tactual. Our concern, of course, is with the visual features 
that serve as sources of information. Usually, operators are not aware of how 
they get the information, only that they become aware of it. The operators, 
in essence, build a cognitive structure or pattern of phenomena which is so 



175 

integrated that it constitutes a functional unit whose properties are more 
than the sum of the parts (i.e., a cognitive gestalt). When we attempt to 
dissect this gestalt into its parts, we lose some of its essential character. 
Nevertheless, in order to develop visual requirements, specific visual fea- 
tures must be identified which serve as the sources of the information re- 
quired to safely and efficiently operate the equipment. 

The location of a visual feature can be specified by its position in 
three planes: fore-aft, lateral or side-to-side, and vertical or up-down. 
To do this, however, requires that reference points in each plane be identi- 
fied. Ideally, the reference points, and hence the location of the visual 
feature should be so determined that they can be generalized across specific 
equipment configurations. For example, a continuous mining operator needs to 
see the cutting head of his machine. If the fore-aft location were specified 
with reference to the operator's head position, the location of the cutting 
head would vary depending on the length of the machine and the location of the 
operator's compartment. However, if the fore-aft position is specified with 
reference to a machine point, in this case the front edge, it does not matter 
what the length of the machine is or where the operator is positioned. 

Specifying the location of visual features, even with the use of general- 
izable reference points, requires that specific assumptions be made about the 
size of the equipment, how the equipment will be used, where it will be used, 
and most importantly, when or where the visual feature should be seen. We will 
address this last point since it is central to our approach. 

The philosophy underlying the specification of visual feature locations 
is that the location specified should represent the last point at which the 
information, if received, can be used by the operator. An example will clar- 
ify this. Consider a road obstruction such as a pile of timber, and its loca- 
tion in the fore-aft plane. How far in front of the vehicle must the operator 
be able to see the obstruction? If he can see the pile 200 feet ahead, that 
would be nice, but it is not really necessary. The location where he must be 
able to see it is a necessary stopping distance ahead of the machine. This 
necessary stopping distance is a function of the speed of the machine, the 
reaction time of the operator, and the inherent stopping capability of the 
machine. 

Specifying the location of in-mine visual features requires assumptions 
to be made regarding how the equipment is being used and the geometry of the 
mine roadways. Unless some simplifying assumptions are made, visibility re- 
quirements will be different for each mine, or area within a mine. It would 
be ludicrous to demand manufacturers to design their equipment to match the 
specific size and use characteristics of a mine. It would not be cost effec- 
tive. To overcome this, simplifying assumptions were made concerning the 
equipment, its use, and mine conditions. These assumptions were based on 
underground observations of equipment, interviews with operators, and review 
of equipment dimensions. They are representative of the vast majority of 
mining situations. 



176 

There are two approaches for specifying the location of visual attention 
locations. The first is to specify "visual windows" of given size and loca- 
tion. The second approach is to specify specific points in space which must 
be visible. Visual windows are defined as areas of unobstructed vision. 
Visual windows must be specified in terms of visual angle, rather than in 
absolute size (unless the distance from the operator to the window is also 
specified). The further away from the observer the window is placed, the 
larger in size it must be to maintain the same visual angle. 

A major problem is encountered in translating the primary requirement of 
seeing a particular visual feature into a visual window specification. The 
problem is that different sized and positioned visual windows would be re- 
quired to see the same visual feature from differently configured equipment. 
Thus, if visual windows were used to specify requirements, a different set of 
windows would have to be specified for each configuration of equipment. 

The second approach to specifying visual requirements eliminates this 
problem by eliminating the need to translate visual features into visual 
angles. The approach specifies the requirements in terms of specific loca- 
tions or visual attention locations which must be visible from the operator's 
position. The key to the approach is to specify the locations with reference 
to machine points. In this way, the requirement will apply to all configura- 
tions of the equipment class. For example, operators may be required to see 
an object on the ground a necessary stopping distance ahead of the machine. 
This point can be located in space as follows: 

Fore-Aft: Front edge of machine + necessary stopping distance 

Lateral: Machine center line 

Vertical: Floor 

The requirement, as written, does not change if the length of the equip- 
ment changes, the operator's posture or position changes, or if the width or 
height of the machine changes. Thus, the requirements are generalizable to 
all equipment with a given class, i.e., all continuous miners, all shuttle 
cars, etc. 

It was the above considerations that led to the adoption of the second 
method for specifying visual requirements in this study. For each class of 
equipment a separate list of requirements was generated. In all cases the 
requirements identify a visual attention location in space (fore-aft, lateral, 
and vertical) in which one or more important visual features were located. 
One goal was to maximize the number of visual features accounted for by using 
a minimum number of visual attention locations. 

The complete list of visual attention locations for continuous miners, 
shuttle cars, and scoops is contained in Sanders (1981). For illustrative 
purposes, we have provided Figure 1, a top view of a continuous miner, showing 



177 



Widest Machine Point 

(WMP (OS) -► 



Machine Center Line n ^ 
(MCL) — — ^— 



Front Edge (FE) 



Operator's Head (OH) 



Rear Edge (RE) 




4 





Operator Center Line 
— — — — (OCL) 



Widest Machine Point 
* (WMP (SS)) 



\ 



> 



+ 



FIGURE 1. - Visual attention locations (fore-aft and lateral) for 
continuous miner operation. 



178 

the location (fore-aft and lateral) of the continuous miner visual attention 
locations. What is not depicted in Figure 1 is the vertical position of the 
visual attention locations. The results of this study will be valuable for 
ultimately prescribing visibility requirements for underground equipment which 
reflect the actual needs of the operators of such equipment. 

ASSESSING WHAT CAN BE SEEN 

There have been numerous approaches suggested in the literature for 
assessing fields of visibility of mobile equipment. These approaches differ 
in terms of complexity, type of information generated, and utility for the 
intended application. Most of the various approaches can be classified into 
three categories: panorama photographic techniques, shadow graph techniques, 
and line-of-sight techniques. A fourth category, miscellaneous, includes 
computer-aided procedures and graphic techniques. Sanders and Kelley (1981) 
discuss each of these approaches noting the advantages and disadvantages of 
each. They conclude that an outside-in line-of-sight technique appears to be 
the best suited for the current application. The procedure is centered around 
a human eye reference measurement instrument (HERMI) which represents the eye 
positions of the 5th percentile female and 95th percentile male performing 
reasonable neck and trunk flexion. HERMI is placed in the operator's cab sim- 
ulating the position of the operator. At each visual attention location, the 
evaluator takes a picture of HERMI in the operator's cab. Examination of the 
photograph allows direct determination of whether the 5th and/or 95th percent- 
ile operator could see that location, and whether to see it the operator would 
have had to flex his/her neck and/or trunk. 

Figure 2 shows pictures of HERMI. The two arcs on HERMI represent the 
eye positions for the 5th percentile female (lower arc) and 95th percentile 
male (upper arc) in a relaxed (slumped) sitting posture. The anthropometric 
data used to construct HERMI represent military personnel as taken from Human 
Engineering Design Data Digest (HEL, 1978) and Anthropometric Data Application 
mannikin (Rogers, 1976). Neck and torso flexion was taken as ±35° as shown in 
Figure 3. The ± value represents mean flexion from military populations. A 
Bureau of Mines project (Contract H01387022, Biomechanics In Low Coal) con- 
cluded that coal miners are not significantly different from military popula- 
tions in terms of linear body dimensions, hence HERMI can be used in the coal 
mine equipment context. 

Several features of HERMI make it unique for underground mining equip- 
ment application. First, the eye arcs are hinged so that they can be oriented 
perpendicular to the ground from any seat back angle, from upright to full re- 
clining. People in a partially reclined position will rotate their neck for- 
ward until their eyes are facing forward. HERMI can imitate this maneuver. 
Second, the eye arcs can be retracted toward the center line of HERMI. In the 
event an obstruction exists in a cab which would prevent torso flexion to the 
full 35° to one side or the other, the eye arc can be shortened to represent 
the restricted space. Third, HERMI is constructed with stand-offs to maintain 



179 




FIGURE 2. - HERMI 



180 






Neck 
Flexion 
Pivot 
Point 



Trunk Flexion 
Pivot Point 



FIGURE 3. - Representation of neck and trunk flexion and resulting 
eye arc used to construct HERMI. 



181 



the proper fore-aft placement of the eye arcs when the operator leans back 
against the seat. 

As configured, HERMI represents reasonable operator postures. An actual 
operator might lean forward to improve visibility or flex more than 35° from 
side to side. It was decided that vehicles should not be designed to require 
such movement from the operator in order to see important visual features. 

HERMI, as designed in this study, however, must be viewed as a first gen- 
eration eye reference measurement instrument. During this project, the fol- 
lowing limitations with the design of HERMI were noted which should be cor- 
rected to improve the validity of the information gathered: 

1. The 5th percentile eye ring assumes that such a person would 
assume the same posture as a 95th male in the cab. Thus, in a 
low canopy cab, the 95th male would have to move his buttocks 
forward in the seat. A 5th percentile female, on the other hand, 
could sit more erect. The current design of HERMI does not permit 
this. The next generation HERMI will be designed to incorporate 
such independent posturing. 

2. HERMI, as designed, does not automatically take into account 
clearance requirements between the eyes and the top of the canopy 
necessary to accommodate the hardhat and cap lamp of the miner. 

3. The positioning of HERMI does not take into account the use of 
"seating aids" such as pillows, wood blocks, etc., which could 
be used by small operators to increase their seating height. 
By incorporating independent posturing of the 5th and 95th 
percentile rings, seating aids could be used. 

A drum head continuous miner was evaluated using the HERMI methodology 
and the visual attention areas identified during this project. The drum head 
continuous miner was evaluated twice, once with the canopy in the highest 
position and once with the canopy in the lowest position. This particular 
machine was selected based on availability. While being representative of 
drum head continuous miners, this machine was not selected because of any 
unique visibility problems or attributes. 

Figure 4 presents a few examples of side-by-side comparison of HERMI 
pictures taken with the drum head miner canopy in the highest and lowest posi- 
tions. The numbers in the upper right corner of each picture correspond to 
the visual attention locations. 

Figure 4 dramatically illustrates the effect of raising or lowering the 
canopy on visibility. With the canopy in the lowest position, vision is 
severely restricted. The situation is considerably better with the canopy 
raised. This is especially obvious in pictures 23, 25, and 26. 



182 




23 




25 








FIGURE 4. - Visibility comparison of a continuous miner with canopy 
in highest and lowest positions. 



183 

Several design features of this particular machine result in restricted 
visibility. The position of the fluorescent lights on the side and in front 
of the operator's cab is one example. The light on the side of the cab pre- 
vents the 95th percentile operator from flexing his torso to see. This is 
shown vividly in picture 25 high. The light in front of the cab obstructs 
vision in the low canopy condition for the small operator as shown in 
pictures 23 and 26 low. 

Another example of design obstructions is the placement of the canopy 
supports and hoses. Pictures 23 high and 25 low and high show how the canopy 
post and hose obstructs vision in the center of HERMI ' S eye arcs, thus re- 
quiring an operator to flex his torso to see the visual attention location. 

The HERMI technique, in conjunction with visual attention locations, is 
a powerful technique for evaluating the visibility afforded the operator by 
the specific design of the equipment. Obstructions are clearly identified, 
and the consequences of redesign are readily apparent. 



184 



TITLE OF PAPER: Disability Glare Studies on 
Underground Mine Personnel 

AUTHOR: Mr. C. L. Crouch (Retired) 

Illuminating Engineering Research 

Institute 
New York, New York 



Mr. Crouch received a B.S. Degree in Electrical Engineering from the 
University of Michigan, and is a Registered Professional Engineer in the 
state of New York. His professional career included service with Holophane 
Company, involved in engineering design and application work; with Wipperman 
Mitchell, Inc., as an illuminating engineer; and with Buffalo-Niagara Corp. 
as industrial lighting and special application engineer. 

In 1944, Mr. Crouch became Technical Director of the Illuminating 
Engineering Society, and Secretary-Technical Advisor to the Illuminating 
Engineering Research Institute. As Technical Director, Mr. Crouch conceived 
and helped produce the first IES Lighting Handbook. He also initiated, 
planned, and coordinated projects in the fields of street/roadway lighting 
and school lighting, and participated in the development of standards and 
recommendations for various types of specialized lighting applications. 

In 1967, Mr. Crouch became Director of Research and Secretary/Treasurer 
of the Illuminating Engineering Research Institute. During this period he 
developed comprehensive research programs covering: 

. basic research in the visual process and the relationship 
of light to visual performance 

. development of characteristics of the optimum visual or 
luminous environment 

. studies of the luminous environment to apply to typical 
conditions found in commerce and industry 

In 1941, Mr. Crouch was the recipient of the Niagara Award; and in 1968, 
the IES Gold Medal. Mr. Crouch is an international lecturer in the field of 
light and vision as related to illuminating engineering; and is the author of 
numerous technical papers resulting from original research in the field of 
illumination engineering. 



185 



Mr. Crouch is affiliated with the following professional organizations 

Member of Illuminating Engineering Society (IES) since 1930 
and Fellow since 1946 

Fellow of the American Association for the Advancement of 
Science 

Member of Optical Society of America 

Affiliate Member, Institute of Traffic Engineers 

Member, U.S. National Committee of the International 
Commission on Illumination 

Member, Council of Educational Facility Planners, Inter- 
national Illuminating Engineer for 51 years 

Member, American Society of Photobiology 



186 



DISABILITY GLARE STUDIES ON UNDERGROUND MINE PERSONNEL 

by 
C. L. Crouch 1 



ABSTRACT 

A recent survey of miners operating both under high seam and low seam 
conditions indicated problems with current types of mine lighting. Seventy- 
eight percent of the miners interviewed had complaints or questions regarding 
the lighting systems from the viewpoint of discomfort glare, disability glare, 
veiling reflections, and after-images. These complaints resulted in the 
question as to whether the underground mining population was more sensitive to 
glare than the aboveground population in commerce and industry. If they were 
more sensitive, then the glare formulas should be changed so that improved 
lighting designs could be made for mine illumination. The U.S. Bureau of 
Mines sponsored a study by the Bituminous Coal Research, Inc., and a joint 
study was carried out by BCR and IERI . A large number of observers were 
tested for disability glare and the results of this study are being presented 
in this paper . 

INTRODUCTION 

In recent years the system of lighting of mines has changed from only 
caplamps to both caplamps and general lighting with the luminaires mounted on 
the machines. In general these luminaires consist of dif fusing-type equipment 
both incandescent and fluorescent. The fluorescent luminaires consist of 
fluorescent lamps enclosed in a cylindrical diffusing housing. This intro- 
duction of general lighting luminaires has greatly changed the visual environ- 
ment, and in general has received favorable reaction of the miners even though 
there are a number of complaints. A survey of their reaction has indicated in 
general that they would not want to revert to the former system of caplights 
only. Seventy-eight percent of the miners interviewed had complaints or 
questions regarding the lighting systems from the viewpoint of discomfort 
glare, disability glare, veiling reflections, and after-images. These com- 
plaints resulted in a serious concern on the part of the Mine Safety and 
Health Administration of the U.S. Government and the U.S. Bureau of Mines. 
The Bureau of Mines wished to correct the situation and instituted a study of 
both discomfort glare and disability glare, first from current lighting 
systems, and second, the sensitivity of miners to the two forms of glare. 



Director of Research, Illuminating Engineering Research Institute, New York, 
New York. 



187 

The Bituminous Coal Research, Inc., and the Illuminating Engineering Research 
Institute have collaborated in making a study of these two phases. 
Dr. Sylvester Guth is reporting at this session on the discomfort glare phase, 
and this paper is concerned with the disability glare portion. 

DISABILITY GLARE 

In 1925, Holladay (1) discovered that disability glare reduced the visi- 
bility of objects or tasks to be seen. He found that for glaring lighting 
units, the glare effect could be represented by an equivalent uniform lumi- 
nance overlaying the object to be seen. In 1928, Stiles (2) of England con- 
firmed the Holladay concept and published a paper in the International 
Commission on Illumination (CIE) proceedings. In 1935 he confirmed the 
formula that Holladay had developed. In 1955 Fry (3) further confirmed the 
concept. Still later, Blackwell (4) developed the modification that the 
equivalent uniform luminance of the glare sources both caused an increase of 
adaptation, thus sensitivity, as well as a loss. The net result, in general, 
was a loss. He developed formulation that would take into account both 
effects. This formula as given in the CIE Report 19/2, Vol. I, is as follows: 

L x RCS for L 
e 

rvp-p = _ 

L x RCS for L 

e 

where L is the luminance of the background of the task without glare and 

L + L 
v 

L = - — . K represents the scatter effect of the rays of light in the eye 

el+aK ' J 

media and "a" is the portion of the visual field occupied by the glare 

sources. "a" is a proportionally constant determined by the angular dimension 

of the surround. L is the equivalent veiling luminance from the glare 

sources. RCS is the relative contrast sensitivity. DGF = the disability 

glare factor. 

PHYSIOLOGICAL BASIS OF DISABILITY GLARE 

Fry (5) and other researchers found that there was a scatter of the light 
from the glare sources through the eye media involving the cornea, the lens, 
the vitreous humor, and the retina itself. This scattering of light caused an 
internal veiling luminance to be superimposed upon the focused image that the 
observer was trying to see. 

EFFECT OF AGE 

Fisher and Christie (6) in 1965 found that there was a definite age 
factor involved in disability glare. Their studies were related to roadway 
lighting. In 1973 and 1974, Italian investigators led by Lucia Ronchi (7) 
determined that the disability glare factor was dependent upon pupil size, and 
therefore the K factor in the above formula changed to a higher value at low 



188 



levels of illumination involved in roadway and mine lighting as compared with 
the higher levels used in interior lighting. 

Blackwell (8) made very comprehensive tests on various age groups and 
with high and low levels of illumination and determined the K factors 
involved. Further he was able to determine the change of the K factor for 
age. For 100 candelas per square meter, K = 10 ra 3 . For 1.7 candelas per 
square meter, K = 10 mi+ . "1113" and "mi/ 1 are as follows: 

013 

Age 20-44 years m 3 = 1.000 

44-64 = 1.000 + .0310(A - 44) 

64-80 = 1.620 + .0725(A - 64) 

mi^ 

Age 20 - 44 years m 4 = 1.500 

44-64 = 1.500 + .0419(A - 44) 

64-80 = 2.338 + .0668(A - 64) 

INSTRUMENTATION 

Fry (9) in 1955 presented a proposed lens for mounting on the front of a 
luminance meter that would proportion the response of the photocell through 
the optical system in accordance with the disability glare effect. This 
concept was further developed in an actual glare lens in 1963 (10). This has 
been used considerably in street lighting in this country. In 1959, Blackwell 
(11) developed a Visual Task Evaluator (VTE) for measurement of visibility of 
tasks in commerce and industry. This consisted of a contrast threshold meter 
that would reduce the unknown task to threshold and then by calibration deter- 
mine an equivalency between that task and a laboratory test object on which 
visibility data had been extensively recorded. Later models were modified and 
the current model includes a limited exposure time of 200 milliseconds to the 
observer. The field of view of this instrument is limited to a range of two 
to three degrees. This therefore records the foveal response to the visi- 
bility of the object. More recently, in order to determine the factor of age 
he was able to introduce into the optical train of the VTE an enlarged field 
of view of 27 degrees subtense. Due to the fact that there is a change with 
pupillary opening and therefore with the level of illumination and with age 
and the variability between observers, the Visual Task Evaluator has now been 
altered to allow an attachment of a disability glare evaluator which inserts 
in the optical train the field of view of 27 degrees. Thus the VTE with the 
attachment can evaluate the visibility of the task without glare and with 
glare. This instrumentation has provided a means of evaluating the sensi- 
tivity of miners under the low level illumination found in the current light- 
ing of mines . 



189 



EVALUATION OF DISABILITY GLARE FROM CURRENT LIGHTING SYSTEMS 

The first phase of the study was to determine from current formulae 
whether current lighting systems being used in mines caused disability glare. 
Seven different systems were put on a continuous miner and later on a bolter 
in a simulated mine environment representing a nominal 0.06 fL wall luminance 
(0.206 candelas per square meter). Several positions were taken around each 
machine for the purpose of making measurements. These positions were pointed 
out by company engineers in charge of the installation of the lighting 
systems. These positions represented critical visual locations where the 
miners would be involved in working around the machines. The results of 
measurements are shown in Tables 1 and 2. You will note a great variation in 
resulting visibility since disability glare factor (DGF) means the percentage 
of visibility still left after the glare effect. These measurements of course 
made use of the current formulation as developed by Blackwell and described 
above . 

EVALUATION OF DISABILITY GLARE SENSITIVITY OF MINERS 

The Visual Task Evaluator with its disability glare attachment was set up 
at the Maple Meadow Mine outside of Beckley, West Virginia, and further at the 
Derby and Prescott mines near Big Stone Gap, Virginia. The test set-up was 
shielded by black curtains, and the general environment was maintained between 
0.06 and 0.07 fL (0.206 & 0.240 candelas per square meter). Part of the time 
a second VTE was operating in another location where a higher level was pro- 
vided between 6.75 and 7.31 fL (23.1 & 25.0 candelas per square meter). 
(Later the VTE being used for the higher level failed and the measurements 
were continued under the low level.) 110 observers were involved in the three 
locations. A number of the 110 observers were not only tested once but also 
came in for a retest . A portion of the tests concerned not only the low level 
luminance but also the higher luminance as well. 

Dr. Blackwell had tested 235 observers in the laboratory for disability 
glare at 1.7 & 100 cd/m 2 (0.49 & 20 fL) . To determine the age effect in 
disability glare the 235 observers were divided into 5 decades of age. 
Further, Dr. Blackwell had access to the studies of Prof. Dr. Werner Adrian 
which made an overall figure of approximately 400 observers tested in two 
laboratories for disability glare. From these combined data Dr. Blackwell was 
able to predict what would occur if the two sets of observers had participated 
under the same conditions that the miners had tested. Taking the average of 
all these predictions this population would have a predicted disability glare 
factor, DGF, equal to 0.582 which includes the effect of age. This DGF value 
accounts for a 41.8 percent loss in visibility. Upon analysis of the 110 
miners Dr. Blackwell found the disability glare factor, DGF equal to 0.598 
which accounts for a 40.2 percent loss in visibility. 



^University of Karlsruhe, Germany. 



190 



TABLE 1. - DGF measurements for the continuous miner 



Position 2 



Lighting system 
15w fluorescent 

1500 ma 

fluorescent 

1500 ma 

fluorescent 

1500 ma 

fluorescent 

1500 ma 

fluorescent 
Incandescent . . . 
(Unshielded) 
Incandescent . . . 
(Shielded) 
Incandescent . . . 
(Unshielded) 
Incandescent . . . 
(Partial shield 
at 45 degrees) 
Incandescent . . . 
(Shielded) 



Position 1 
(Tl) ** 
(T2) 0.018 

(T3) 0.193 

(T4) 0.473 

(T5) 0.557 

(T6) ** 

XXX 

(T7) 0.677 

XXX 
XXX 



Position 3 
(T23) 0.043 
(T28) 0.806 

(T26a)0.670 

(T15) 0.241 

(T26b)0.487 

XXX 

(T19) 0.645 

XXX 

(T22) 0.104 
(T20) 0.977 



Posi tion 4 
(T24) 0.791 
(T29) 0.578 

(T25) 0.617 

(T16) 0.552 

(T27) 0.574 

(T17) 0.317 

(T18) 0.492 

XXX 
XXX 

(T21) 0.311 



A. 
B. 



(T10) 1.000 

(T14) 0.644 

(T12) 0.291 

(Til) 0.815 

(T13) 0.477 
(T9) ** 



xxx 



(T8) 



** 



xxx 



xxx 



TABLE 2. - DGF measurements for the Acme bolter 





Lighting System 


Position 1 


Position 2 


Position 3 


A. 


1500w fluorescent 


(Tl) 0.116 
( T 2 ) ** 
(T3) 0.411 
(T4) 0.637 
(T5a)0.679 

(T5b)0.395 


(T6) 0.229 
(T7) 0.071 
(T8) 0.360 
(T9) 0.573 
(T10b).025 

(T10a).400 


(Til) 0.100 


B. 


1500 ma fluorescent 


(T12) 0.100 


C. 


1500 ma fluorescent 


(T13) 0.306 


D 


Incandescent 


(T14) 0.039 


F, . 


Incandescent 


(T15) 0.358 


F. 


(Shielded) 

Incandescent 






(Unshielded) 





xxx - Position was not measured 
** - DGF could be calculated 



191 



From the analysis of the writer and Dr. Blackwell comes the conclusion 
that as far as disability glare is concerned, the miners were in agreement 
with the studies of Blackwell and Adrian which had been conducted under more 
carefully controlled laboratory conditions. There had been very large 
variations among the mining observers in response to disability glare as 
measured under field conditions. 

SIGNIFICANCE OF THE DISABILITY GLARE EVALUATIONS 

It would appear from the analysis to date (the analysis is still con- 
tinuing) that one can expect roughly a 40 percent loss or more in visibility 
(see tables 1 & 2) . If one uses the figure of 40 percent loss of visibility 
and applied it to interior lighting such as office and commercial lighting, 
one could expect a visual performance loss between 20 to 25 percent for the 
tasks in these environments. Probably under mining conditions where the visi- 
bility of an object is poor and the illumination level low, the loss of visual 
performance would be much greater. One would need to have the visibility 
measurements of actual objects to be seen in mines to carry out a visual 
performance analysis for the mine environment. 

REFERENCES 

(1) M. Luckiesh and L. L. Holladay, Trans. IES, ^0, (1925). 
L. L. Holladay, J. Opt. Soc . Am., 12, p. 279, (1926). 

(2) W. S. Stiles, Proc. CIE, p. 220, (7928). 

(3) G. A. Fry, Ilium. Eng.,_50, p. 31, (1955). 

(4) H. R. Blackwell, Ilium. Eng . , .50 , p. 286, (1955). 
H. R. Blackwell, JIES, 9_, p. 205, (1980). 

H. R. Blackwell, CIE Report 19/2, _1, (1981). 

(5) G. A. Fry, Ilium. Eng., 49, p. 98, (1954). 

(6) A. J. Fisher and A. W. Christie, Vision Res., J5> P- 565, (1965). 

(7) A. Mariani and G. Longobardi, Atti della Fondazione Giorgio Ronchi , _28, 
p. 751, (1973). 

L. Ronchi, R. Sulli, G. Longobardi, Atti della Fondazione Giorgio 
Ronchi, 29, p. 965, (1974). 

(8) H. R. Blackwell, JIES,2> P- 205 » (1980). 

(9) G. A. Fry, CIE Proc, (1955). 

(10) G. A. Fry, B. S. Pritchard, H. R. Blackwell, Ilium. Eng., _58, P- 120, 
(1963). 

(11) H. R. Blackwell, Ilium. Eng., 54, p. 317, (1959). 
H. R. Blackwell, Ilium. Eng., 65, p. 267, (1970). 



192 



TITLE OF PAPER: Determination of Safety Light- 
ing Needs for Exterior and 
Interior Areas of Coal 
Preparation Plants 

AUTHOR: Richard L. Vincent 

Illuminating Engineer Research 

Institute 
New York, New York 



Mr. Vincent received a B.S. Degree in Architecture from the University 
of Michigan, Ann Arbor, Michigan. 

He has been associated with the Illuminating Engineering Research 
Institute (IERI) since 1976, and was Assistant to the Director of Research 
from 1976 to July 1981. He has been a member of the Illuminating 
Engineering Society (IES) since 1979, and served on the IEW Office Lighting 
Committee. 

Mr. Vincent has conducted studies of office lighting in New York, 
safety lighting on aircraft carriers, and three coal- industry projects 
which involved minimum safety lighting requirements for coal preparation 
plants, minimum safety lighting requirements for draglines and shovels, and 
psychophysical testing of underground miners. 



193 



DETERMINATION OF SAFETY LIGHTING NEEDS FOR EXTERIOR AND 
INTERIOR AREAS OF COAL PREPARATION PLANTS 

by 

Richard L. Vincent 1 



ABSTRACT 

A study was conducted to determine what levels of light are required for 
safe working conditions to be maintained in and around coal preparation plants, 
Visual Task Evaluator measurements were made at three preparation plants at 
Beckley, West Virginia. Fifty-one tasks were selected and measured from which 
levels of light required by both young and older miners were determined. 

INTRODUCTION 

Proposed regulations for the illumination of coal preparation (1) plants' 
interior and exterior areas were discussed in a March 1977 meeting(2) of the 
Illuminating Engineering Society of North America, IESNA, Committee on Mine 
Lighting. During the Committee meeting it was emphasized that illumination 
levels required for safety of workers should be obtained. 

A study to find the safety levels of illumination was sponsored by Bitu- 
minous Coal Research, Inc., Pittsburgh, Pennsylvania. The field testing and 
analysis were conducted by the Illuminating Engineering Research Institute of 
New York City with the supervision of Mr. C. L. Crouch, the IERI Director of 
Research and the author serving as the investigator. 

The IESNA Committee selected three coal processing plants in Beckley, 
West Virginia for the study. Of the plants, one was old, one new, and the 
third had new yard lighting. The study took place in May 1977. The Visual 
Task Evaluator, VTE, was used to measure the visibility of 51 selected visual 
tasks (see figures in Appendix) . In order to keep a constant light level dur- 
ing the visibility measurements, most tasks were measured at night or where 
daylight was minimized. The geometric distribution of light produced by each 
plant's lighting system was utilized in the visibility measurements. Illumi- 
nation requirements were then determined for each task based on the visibility 
of the critical details to be seen (see Tables 1A-1B) . Reflectance values for 
each task were obtained based on the Munsell System. 



■'■Associate Research Administrator, Illuminating Engineering Research Insti- 
tute, New York. 



194 



VISUAL TASK EVALUATOR 



The Visual Task Evaluator, VTE, (3) is a contrast threshold meter developed 
to assess the visibility of unknown details in the real working world. An op- 
erator of the VTE looks through the instrument at a detail of concern and ad- 
justs an internal veiling luminance which is superimposed over the detail. As 
the veiling luminance is increased, the contrast of the detail is reduced. 
The operator adjusts the veiling luminance until the detail can just barely be 
seen. The point of bare seeability is called the threshold for the detail be- 
ing measured. At threshold, all objects become equal in visibility; therefore, 
they can be compared to find what factor would make them equally visible above 
threshold. This comparison is important because it allows unknown details in 
the field to be compared with known details which have been studied in the 
laboratory. Tests have been conducted on college students with normal vision 
to determine threshold data on a standardized test object, a 4-minute disc 
(whose diameter subtends 4 minutes of arc at the eye). The relation of how 
the threshold contrast for the 4-minute disc varies with given light levels is 
an established function (see Figure A) and is part of the CIE Report 19/2 which 
relates visual performance to light level (4). The operator of the VTE has pre- 
viously run through a calibration procedure, based on the 4-minute disc, which 
produces a calibration curve. The measurement made with the VTE can then be 
related through the calibration curve to the laboratory threshold data. An 
Equivalent Contrast, C, necessary to make the 4-minute disc equal in visibility 
to the unknown detail can then be determined. 

DISCUSSION OF FIELD MEASUREMENTS 

The VTE was brought to each of the three test sites where knowledgeable 
personnel described the working operations of the plant and pointed to specific 
critical visual tasks which needed to be seen for safe and productive work. 
Critical tasks were selected both in the interior and exterior spaces of the 
old and new plants. From the interior of the old and new plants critical vis- 
ual tasks were selected to include: the control rooms, the electrical equip- 
ment rooms, workshops, storerooms, walkways, fixed processing equipment, ma- 
chine wells, elevators, and a bathhouse (see Table 1A) . The exterior areas 
which were surveyed included: active building entrances and exits, storage, 
coal loading and unloading, .conveyor belts, loading platform, walkways, active 
railroad tracks, track switching points, parking lots, shaft landings, and re- 
fueling areas (see Table IB). 

The various tasks were measured using the VTE over a two-night period. 
In making VTE measurements in some locations of both the old and new plants, 
the levels of illumination were so low that measurements could not be made 
through the instrument because of the absorption factor of the VTE optics. 
Therefore supplementary lighting was placed so that light came from the same 
general direction as the lighting system would have produced if operating at 
a higher level of light emission. In some cases, such as the tunnel /conveyor 
area leading to the exterior depositing area, the supplementary lighting could 
not be placed to throw light at the same angles that the general lighting 



195 




FIGURE A. - The Visual Task Evaluator (VTE) is designed to use 
0.2 second exposures that permit more realistic 
field measurements. 



1000 
500 

























































































































































































































































































































































































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50 100 200 



LUMINANCE IN FOOUAM8ERTS 



FIGURE A. - Relationship for the standard 4' target (0.2 second 
exposure time, 99 percent accuracy, and a field 
factor 8.00) to which practical tasks are equated. 



196 

system produced. The distribution and direction of light do alter the visi- 
bility of the tasks being viewed; therefore, the values for this area are not 
altogether correct but rather indicate a general order of visibility. 

REQUIRED ILLUMINATION BASED ON AGE 

Recommendations of illumination have been based on the average of young, 
normally sighted adults in their 20' s. Work has been ongoing to determine the 
additional illumination needed as a person ages. The reference, "Visual Per- 
formance Data for 156 Normal Observers of Various Ages" (5), shows that for 
static viewing of the details of the task (not scanning), there is a factor by 
which the visual performance data of the 20-year old population can be adjusted 
to account for each decade of age beyond 20 years of age. Through a brief tele- 
phone survey by the then IESNA chairman, George Evans, there was an indication 
that 40-50 years might well represent the average age of the people working in 
and around the coal preparation plants; therefore, the calculations of illumi- 
nation required have been made for the 20-30 year decade and the 40-50 year 
decade. 

CONCLUSION AND RECOMMENDATIONS 

In reviewing the illumination of the various tasks for the interior spaces 
of the preparation plants, both old and new, 4-5 footcandles would be required 
to meet the needs of most visual tasks for the 20-30 year olds and the 40-50 
year olds. For the exterior areas, 4-6 footcandles would be required to meet 
the needs for the same age groups. Certain tasks exceed these recommendations 
and consideration should be given to altering the contrast of these tasks (6). 
In another coal-related research it was found that the contrast of metal steps 
could be improved by painting the worn metal edge with a safety yellow while 
the remaining portion was painted a battleship gray. This enhanced contrast 
increased the visibility of the detail approximately five times. This princi- 
ple of accentuation of the contrast of the detail as seen against its back- 
ground could be applied to the tasks which required more illumination than the 
majority of tasks to be seen. 



197 



REFERENCES 

1. Surface Coal Mines and Surface Work Areas of Underground Coal Mines. 

Federal Register, Thursday, January 13, 1977, Part IV. 

2. Minutes of the IESNA Task Committee on Exterior Lighting of Coal Mines, 

May 2, 1977 meeting. 

3. Development of Procedures and Instrument for Visual Task Evaluation. 

H. Richard Blackwell, Illuminating Engineering, April 1970, page 267. 

4. An Analytical Model for Describing the Influence of Lighting Parameters 

upon Visual Performance. International Commission on Illumination, 
CIE, Report 19/2, March 1979. 

5. Visual Performance Data for 156 Normal Observers of Various Ages. 

0. M. Blackwell and H. R. Blackwell. Journal of IES, Vol. 1, No. 1, 
October 1971, page 3. 

6. Survey of the Illumination Needs of Tasks for Safe Work Performance on 

Walkways and Work Areas of Mobile Surface Mining Machines. C. L. 
Crouch and Richard L. Vincent. Report to the Mine Safety Appliance 
Company by the Illuminating Engineering Research Institute, January 
1980. 



198 



APPENDIX 

TABLE 1A. - Measurements of Illumination needs of tasks to be seen 
in interior spaces of new and old coal preparation plants 



Tasks and Location 







Foot- 


Foot- 




% Re- 


candles 


candles 


Munsell 


flec- 


20-30 


40-50 


index 


tance 


yr-olds 


yr-olds 



1. Control room & stations 
Old plant 

a) Identification plate N2 

(white on black) 

New plant 

b) Identification plate 

(white on black) 

c) Identification plate 

(white on red) 

d) Identification plate 

(see Figure l(A-D)) 

2. Electrical equipment rooms 
Old plant 

a) Position of magnetic N6.5 

starter switch 

New plant 

b) "On" position of switch. . . . 
(pressed down) 

c) Identification plate 

(black on -white) 
(see Figure 2(A-C)) 

3. Shops 
New plant 

a) Chain on steel plate 

b) Jackhammer and chain 

c) Tools on the floor 

(see Figure 2(A-C)) 

4. Storerooms 

Old plant - inactive storage 

a) Port N4.5 

New plant - inactive storage 

b) Cylindrical units in aisle 

c) Port 

New plant - active storage 

d) Skid N6.5 

(see Figure 4(A-D)) 



3.8 



36.9 



16.0 



36.9 



0.18 



0.05 



0.16 



1.90 



0.25 



N2 


3.8 


0.32 


0.39 


5R 5/12 


20.7 


2.42 


2.90 


5G 6/6 


30.0 


27.00 


76.67 



0.07 



N7.5 


51.4 


1.56 


2.43 


N9 


79.7 


1.25 


1.88 



5YR 5/2 


19.7 


2.54 


3.05 


N6 


30.4 


1.05 


1.27 


N4 


12.6 


0.11 


0.14 



0.24 



N6.5 


36.9 


5.42 


10.84 


N4 


12.6 


2.78 


3.73 



3.39 



199 



TABLE 1A. - (continued) 



Tasks and Location 

5. Walkways 
Old plant 

a) Edge of steel grated step 

b) Blackened yellow hose 

New plant 

c) Large clamp on the floor 

d) Piece of coal in wet slick. . . . 

e) Steel bar resting on stair-... 
rail 

f) Wet rubber mat in walkway 

g) Steel bar resting on column... 

h) Pail near column 

i) Electric cable on floor 

(see Figure 5(A-I)) 

6. Fixed processing equipment 
Old plant 

a) Sluice box on floor 

(see Figure 6A) 

7. Machine well 
New plant 

a) Floor flange guard 

(see Figure 5G) 

8. Elevators 

Old plant - man lift 

a) Platform on belt 

b) Handhold on lift 

c) Entrance platform 

New plant - regular elevator 

d) Elevator threshold 

(see Figure 8(A-D)) 

9. Bathhouse 
New plant 

a) Doorwedge on floor 

b) Green hose on bath floor 

(see Figure 9(A-B)) 

10. Conveyor — belt walkway 
Old plant - unguarded 

a) Roller edge 

b) Edge of belt 

New plant - unguarded 

c) Roller edge 

d) Control wire (see Fig. 10(A-D)) 



Munsell 
Index 



N5 
N3 

N4 
N2 
N5 

N5 
N5 
N5 
N5 



N4.5 



N5 



N5 



% Re- 
flec- 
tance 



20.4 

7.1 

12.6 
3.8 

20.4 

20.4 
20.4 
20.4 
20.4 



16.0 



20.4 



20.4 



Foot- 
candles 

20-30 
yr-olds 



0.17 
0.77 

3.25 
0.16 
2.30 

1.57 
0.74 
1.13 
0.25 



0.30 



0.25 



0.49 



Foot- 
candles 

40-50 
yr-olds 



0.24 
1.20 

3.73 
0.22 
2.94 

1.86 
0.98 
1.42 
0.34 



0.41 



0.34 



N4 


12.6 


0.79 


1.19 


N5 


20.4 


0.20 


0.25 


N5 


20.4 


1.57 


1.86 



0.74 



N6.5 


36.9 


3.25 


4.74 


N5.5 


24.9 


0.62 


0.70 



N4 


12.6 


0.28 


0.37 


N4 


12.6 


0.35 


0.40 


N7 


43.3 


0.10 


0.13 


N4 


12.6 


1.43 


1.59 



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208 



TABLE IB. - Measurements of illumination needs of tasks to be seen in 
exterior spaces of new and old coal preparation plants 



Tasks and Location 



1. Active entrances & exits 
New plant 

a) Plant doorway threshold 

(see Figure 1A) 

2. Storage 
New plant 

a) Strap steel ends (see Fig. 2A) 

3. Coal load/unload areas 
New plant 

a) Edge of column holding 

refuse collector 

b) Dump switch 

(see Figure 3(A-B)) 

4. Conveyors 

Old plant - unguarded 

a) Emergency shutdown cord 

New plant - unguarded 

b) Belt edge in tunnel 

(see Figure 4(A-D)) 

5. Loading platform 
New plant 

a) Chain for loading dock 

(see Figure 5A) 

6. Pa ths /walkway s 
New plant 

a) Edge of wheel in path 

b) Path to phone & dumper 

c) Sledgehammer in tunnel 

d) Metal conveyor support 
in tunnel 

e) Dark/wet mat in tunnel 

(see Figure 6(A-E)) 

7. Active tracks 
New plant 

a) Rail switchblade 

(see Figure 7A) 

8. Track switch points - active 
New plant 

a) Position of switch handle.... 

b) Discarded switch handles 

(see Figure 8(A-B)) 

9. Parking lots - new plant 

^ Auto barrier (curb) (Fig. 9A) 







Foot- 


Foot- 




% Re- 


candles 


candles 


Munsell 


flec- 


20-30 


40-50 


Index 


tance 


yr-olds 


yr-olds 



N5 



N4 



N5 



N3 



N4.5 



20.4 



12.6 



20.4 



7.1 



15.9 



0.14 



0.21 



0.39 



1.13 



3.77 



1.86 



2.54 



N4 


12.6 


3.02 


3.73 


N3 


7.1 


0.45 


0.54 



N3 


7.1 


0.03 


0.04 


N3 


7.1 


0.62 


0.85 



0.54 



N4 


12.6 


6.35 


9.92 


N3.5 


9.7 


0.62 


0.88 


N5 


20.3 


1.28 


1.87 


N3.5 


9.7 


0.08 


0.10 



1.55 



5.97 



N4.5 


15.9 


1.26 


1.82 


N4.5 


15.9 


1.19 


1.26 



N5 



20.4 



0.37 



0.47 



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213 



TITLE OF PAPER: Cost Effective Illumination 
of Underground Machinery 

AUTHOR: Mr. John R. Parker, P.E. 

Booz, Allen & Hamilton Inc. 
Cleveland, Ohio 



Mr. Parker is an Associate, Technology Management Group, with Booz, 
Allen & Hamilton Inc., and has 12 years' experience designing, developing, 
and testing mobile, underground mining machinery for original equipment 
manufacturers. He has had supervisory experience in developing continuous 
miners, mobile haulage systems, roof bolters, and miscellaneous supply 
handling and haulageway vehicles. He has a bachelor degree in Mechanical 
Engineering from Ohio State University, and is a registered professional 
engineer. 

As chief engineer for one company, he was responsible for the selec- 
tion and integration of illumination equipment into the company's full 
product line. Since 1979, he has been with Booz, Allen & Hamilton, a 
consulting firm which has had several Bureau of Mines' contracts to "Demon- 
strate Coal Mine Illumination Systems." Presently, as a part of one of 
these contracts, he is working to develop a low-glare illumination system 
particularly suited to the needs of thin seam, direct current-powered 
machinery. In this capacity, he has become particularly concerned with the 
size of luminaire requirements for improved visibility, and the effects of 
illumination system design on the profitability of mechanized mining 
operations. 



CO-AUTHOR: William F. Hahn, Ph.D. 

Principal, Technology Management Group 
Booz, Allen & Hamilton Inc. 
Cleveland, Ohio 



214 



COST EFFECTIVE ILLUMINATION OF UNDERGROUND MACHINERY 

by 
John R. Parker, P.E. 1 and William F. Hahn, Ph.D. 2 



ABSTRACT 

Although supplemental illumination systems have been developed and retro- 
fitted to the nation's underground coal mining machinery, the task of illumi- 
nating the work place is not complete because mine operators desire more eco- 
nomical lighting solutions. Mine operators feel that not only were lighting 
systems expensive to purchase and install, but that costs for maintaining them 
were higher than expected. In addition, they have seen that new, lower power 
incandescent luminaires are suited to many mining situations and that these 
across-the-line systems provided desired hardware and maintenance savings. 
As a consequence, they believe more economical lighting solutions are feasible. 

Unfortunately, many of the lighting system manufacturers are not con- 
vinced that more economical systems are feasible. They view low power lumi- 
naires as satisfactory only for low seams. Across-the-line systems are con- 
sidered to be satisfactory for direct current machinery. They feel that their 
high power luminaires are technically and economically superior for the major- 
ity of work place situations. 

Certainly operators desire more economical solutions, but significant 
progress cannot be expected until the mine operator and the manufacturer agree 
on the requirements for cost-effective solutions. Once there is an agreement, 
lighting solutions at representative sites can be evaluated and specific rec- 
ommendations for improving mine lighting can be developed. A collective agree- 
ment on these recommendations will result in a master plan for future mine 
lighting development. 

This paper is intended as a baseline definition of the general require- 
ments for cost effective illumination of the work places of an underground 
coal mine. 



Associate, Booz, Allen & Hamilton, Inc., Cleveland. Ohio 
2 Principal, Booz, Allen & Hamilton, Inc., Cleveland, Ohio 



215 



COST EFFECTIVE ILLUMINATION OF UNDERGROUND MACHINERY 

The Federal Coal Mine Health and Safety Act of 1969 not only required, 
but started the development of lighting systems which would supplement the 
illumination provided to the underground coal miner by his portable, battery 
powered cap lamp whenever he worked in places where fundamental, self-propelled 
mining machinery was used. Several sizeable projects had to be completed be- 
fore supplemental lighting systems could be developed and retrofitted to the 
nation's underground coal producing machinery. These projects addressed the 
following issues: 

• Work place lighting requirements. 

Suitable lamps and power levels . 

Explosion-proof enclosures with windows. 

Circuits to start and run enclosed lamps on mine power 
systems. 

Machinery compatible lighting systems for all nation's 
fundamental work place machinery. 

These projects have been completed, and the goal of the 1969 Act has been 
reached as a result of a vigorous and cooperative effort by an industrial team 
comprised of the U.S. Bureau of Mines, the lighting equipment manufacturers, 
the Mine Safety and Health Administration, the Bituminous Coal Operators Asso- 
ciation, the United Mine Workers of America, and many others. Today, most of 
the work places where fundamental mining machinery is used are illuminated 
(see Figure 1) by retrofitted machine lighting systems. These systems were 
largely comprised of high output luminaires, (high pressure sodium vapor and 
high or super-high output fluorescent lamps) which are capable of illuminating 
coal surfaces 3 to 4 meters (10 to 13 feet) away to a minimum reflective light 
intensity of 0.06 foot lamberts. In addition, some lower power, shorter range 
fluorescent systems were used extensively on longwall chocks and shields, and 
some shorter range, incandescent machine luminaires were used on low seam ma- 
chinery after mid-1979. 

Having retrofitted all of their production machinery with supplemental 
work place illumination systems, and complied with the laws resulting from 
the 1969 Act, mine operators are now concentrating on their fundamental work 
task — mining coal profitably. Because most operators feel that lighting sys- 
tems were expensive to purchase and install, and that maintenance costs were 
higher than expected, they are searching for ways to reduce the lighting costs 
on operating machines. 

Many operators believe that more economical lighting solutions are feas- 
ible for their equipment. They have witnessed the growing use of smaller, 



216 




FIGURE 1. - Supplemental work place illumination has been provided. 



COMPETIVE 

FUEL 
SUPPLIERS 



STOCK 
HOLDERS 




FIGURE 2. - Model of mechanized mining economy. 



217 

lower power incandescent systems which were believed to have had insufficient 
capacity to meet federal illumination requirements and they also feel that 
these across-the-line systems could provide them with substantial hardware 
and maintenance savings. Because similar across-the-line incandescents have 
long been used as mobile machinery headlights and as stationary rail station 
lights, operators know that additional power boxes containing either ballast 
or d.c. to a.c. inverters are not necessary, that regulated lamp output isn't 
necessary, and that smaller, more easily relamped fixtures are feasible. 

Unfortunately, most of the mine lighting system manufacturers are not 
convinced that more economical lighting products are feasible. Many view the 
use of low power luminaires as satisfactory only for low and thin seam equip- 
ment, and the use of across-the-line systems as satisfactory for direct cur- 
rent machinery which cannot otherwise be operated reliably. They feel that 
their high power sodium vapor and fluorescent systems are technically and 
economically superior for the majority of work place situations because: 
1) more than adequate power allows fewer luminaires to be used, 2) ballasts 
provide desirable output regulation, and 3) these lamps have substantially 
longer life. 

Certainly mine operators should seek to economize their operations, but 
it appears that significant economic relief cannot be expected until lighting 
manufacturers can provide equipment which is clearly responsive to both the 
technical and economic requirements of a mechanized mining operation. At 
present, it seems that no economic progress can be expected because lighting 
manufacturers and mine operators cannot agree on the requirements for cost 
effectively illuminating the work places of a coal mine. 

HOW DO YOU COST EFFECTIVELY ILLUMINATE? 

The coal operator will illuminate work places cost effectively when, over 
the long term life of the machinery, he provides a lighting system which meets 
the application requirements while holding the costs for providing extraction 
resources. Surely, lighting systems must be safe for mine use and they must 
provide effective work place illumination throughout the life of the machine. 
The costs of providing and maintaining lighting systems on fundamental ex- 
traction machinery must be absorbed in the normal long-term costs for provid- 
ing machinery, operating labor, and maintenance labor. 

Figure 2 is a model of the mechanized mining economy. Mechanized extrac- 
tion activities such as coal winning, coal loading, and roof bolting are fun- 
damental to the business. A coal product results from the use of mining re- 
sources which are supplied at a cost to the business. These resources are 
coal reserves, machinery, extraction labor, maintenance labor, construction 
labor, and construction supplies. Resources are provided because compensation, 
payments, and royalties are distributed from the revenues of coal product sales 
and the investments of stockholders and lenders. 



218 



Because supplementary lighting systems primarily provide safety, rather 
than production benefits, the retrofit of these systems onto extraction ma- 
chinery was not expected to alter the volume of coal product. Since that 
product competes with alternative fuels, additional revenues cannot be ex- 
pected to result from the addition of mine lighting. Consequently, the costs 
for providing mine lighting must be absorbed amongst the normal costs for pro- 
viding resources. Since lighting systems affect the costs of providing ex- 
traction resources, a mine, on the long term, must provide lighting without 
incurring additional costs for providing extraction resources. Since ma- 
chinery and maintenance costs are expected to be higher, extraction labor 
costs must be lower. 

Subsequently, a mine operator can assert that he has provided cost- 
effective illumination when he has economically met the requirements for ap- 
plying lighting systems. He has done this when he can assert that: 

Safe lighting systems are used. 

These systems provide effective long-term illumination. 

Extraction labor costs are lower because of lighting. 

Maintenance labor costs are about the same as before lighting. 

Machinery renewal costs are about the same as before lighting. 

In the following sections, supporting requirements for each of these key 
subordinate assertions are developed collectively, these support requirements 
form a comprehensive guide for evaluating the cost effectiveness of specific 
illumination systems and for identifying opportunities for more cost effec- 
tively illuminating the work places of an underground coal mine. 

YOU COST EFFECTIVELY ILLUMINATE WHEN SAFE LIGHTING SYSTEMS ARE USED 

The coal operator must provide and maintain safe lighting systems. He 
has done this when a safe design is used, the Mine Safety and Health Adminis- 
tration (MSHA) agrees that the design, installation, and operation meets fed- 
eral safety requirements, the appropriate state bureau of mines agrees that 
state requirements are met, and the system is maintained as designed and ap- 
proved . 

Safe Lighting Systems Are Used When a Safe Design is Used 

A lighting system is safe for underground mine use when people are not 
endangered by the equipment. People must be protected from explosion, elec- 
trical shock, contact with hot or moving parts, and blinding light. 



219 



Sparks should be prevented from igniting methane . Sparks can be 
contained within explosion-proof enclosures or limited to low 
levels which cannot cause ignition. 

Coal dust ignition should be prevented . Coal dust buildup should 

be prevented or diluted with rock dust. Surface temperatures must 

be sufficiently below ignition threshold - MSHA allows a maximum 
of 150°C. 

High voltage shock protection is required . Contact with shocking 
voltage potential must be avoided by placing power components within 
grounded enclosures which can be de-energized when power components 
must be examined or serviced. Conductor cables must be properly in- 
sulated, sized, and maintained. Power devices must limit short 
circuit current and overload current which could deteriorate cable 
insulation. Cables must be protected from mechanical abuse. 

Personnel should not be exposed to moving parts and hot surfaces . 
Selective location or mechanical guards can be used to prevent ex- 
posure to hot surfaces or moving parts. 

Safe Lighting Systems Are Used When MSHA Says Federal Requirements Are Met 

A machine lighting system must meet Mine Safety and Health Administration 
requirements for electrical equipment, 30 CFR 18, and for work place illumina- 
tion, 30 CFR 75.1719. 

MSHA "certifies" explosion-proof luminaires and power system enclosures . 
Power enclosures must be constructed in accordance with standards and 
must pass an explosion test. Additional heat tests and mechanical im- 
pact tests are used to assure that the mechanical integrity of explosion- 
proof fixtures will be maintained in service. The MSHA certification 
asserts that the components are safe for mine use when they are properly 
used. 

MSHA grants a machine "approval" which allows lighting systems to be 
used . The machine approval is granted to the original equipment manu- 
facturer or to the coal mine operator. The approval establishes the 
fact that MSHA has reviewed the machine for personnel hazards. Elec- 
trically, they have principally confirmed that "certified" power en- 
closures are used safely, that adequate overcurrent and short circuit 
protection is provided, and that the machine is properly grounded. 
Mechanically, the approval assures that guards prevent exposure to 
moving parts, that cables are protected from damage, and that construc- 
tion facilitates inspection and maintenance. 

MSHA inspects work place illumination . MSHA district inspectors use 
go/no go meters to establish compliance with the requirements for 
supplemental illumination as defined for specific machines by 



220 

30 CFR 75.1719-1. A minimum surface luminous intensity of 0.06 foot 
lamberts must be established by the meter when surfaces are at the 
distances established by the standard. The distance of illumination 
is established by the machine type, the seam height, the seam width, 
and machine width. The distance of illumination may vary from 1.5 to 
4.5 meters (5 feet to 15 feet). 

MSHA gives a prior-to-installation illumination approval . A Statement 
of Test and Evaluation (S.T.E.) is issued by MSHA when a lighting system 
is evaluated prior to installation by their Beckley Electrical Testing 
Laboratory. An S.T.E. is based on incident light readings taken on a 
machine model inside a coal mine simulator. A machine with an S.T.E. 
lighting system is not inspected using a go/no go meter unless that 
system is not properly installed or maintained. 

Safe Lighting Systems Are Used When State BOM Says State Requirements Are Met 

Most of the States with deep underground coal reserves have a department 
such as a bureau of mines which establishes and enforces state safety require- 
ments. While most have regulations which conform with federal requirements, 
some have additional or stricter regulations. Kentucky, for example, requires 
headlights on work place machinery. Pennsylvania has many additional require- 
ments and they conduct an investigation which results in a state Bituminous 
Face Equipment (BFE) approval. These state agencies should be consulted when 
new systems are being designed. 

Safe Lighting Systems Are Used When the Systems 
Are Maintained as Designed and Approved 

Machinery must be maintained as designed and approved. Mine foremen, 
federal inspectors, and state inspectors are responsible for assuring that 
machinery is properly maintained. The explosion-proof integrity of electrical 
systems is of primary concern because defects are hazardous to the entire min- 
ing crew. 

YOU COST EFFECTIVELY ILLUMINATE 
WHEN SYSTEMS PROVIDE EFFECTIVE LONG-TERM ILLUMINATION 

A lighting system cannot be cost-effective unless it provides effective 
long-term work place illumination. This happens when lights operate under ex- 
pected conditions, the operators of the equipment see better, and future illu- 
mination needs can be met easily. 

Systems Provide Effective Long-Term Illumination 
When Lights Operate Under Expected Conditions 

The lighting system must be able to start, run, and turn off the lumi- 
naires whenever the machine must operate. This can be difficult because the 



221 



lamps are in explosion-proof enclosures which raise lamp ambient temperatures 
and because mine voltage sources, particularly direct current sources, are 
unregulated. 

Lamps should start and restart on low voltage . Fluorescent, high 
pressure sodium vapor and mercury vapor lamps may be difficult to 
start, particularly when the machine voltage is very low. Enclosed 
lamps should start at ambient lamp temperatures from 10°C to 100°C 
(50°F to 212°F). Starting should be reliable at these extremes on 
low voltage. 

Direct current systems must operate on high voltage . Direct current 
machinery nominally powered at 250 volts d.c, can be expected to see 
actual sustained voltage in excess of 375 volts d.c. (150%). A con- 
stant load (impedence) will draw a higher current (150%) at 375 volts 
than would be expected at a 250 volt rating. This higher current also 
increases resistive heat losses by 225%. Since less than a 15% over 
voltage is normally expected (utility voltage regulation), components 
must be sized to conduct the additional current (150%) and to dissi- 
pate the additional heat (225%) expected when mine voltage is high. 

Direct current systems must survive high transient voltages . On d.c. 
machinery, the motors and long power supply cables store energy when 
current flows. This energy is discharged whenever contacts open and 
disrupt the normal current flow. Load voltages can rise several times 
as a result of this inductive discharge. Power components must sur- 
vive transient voltage peaks or be isolated from them by adequate 
surge suppression systems. 

Systems Provide Effective Long-Term 
Illumination When the Operators See Better 

As a result of the new illumination system, the equipment operator should 
be able to see better. This result is not always guaranteed by problem solving 
methods. For example, some thin seam work places which use wire-rope propelled 
machinery are exempted from federal illumination requirements because the op- 
erator could not see when state-of-the-art lighting systems were installed. 
Three miners work from roving positions to operate the machines. While coal 
surfaces were properly illuminated, the luminaires could not be shielded from 
the miners view. The glare from these direct view luminaires contrasted great- 
ly with the view of ribs and roof surfaces. The workmen were disabled because 
their eyes could not rapidly respond to the change of view. As a consequence, 
MSHA exempted these machines until no-glare luminaires are developed. ? 



3 The U.S. Bureau of Mines has two contracts which may develop suitable lumi- 
naires: J01000084 - Mine Safety Appliance Co.; and J0188077 - Booz, Allen 
& Hamilton, Inc. 



222 



Hazards and task objects should be discernible . Visibility is improved 
when the miner can readily see hazards and task objects. These are seen 
when they are discernible from their surroundings. Discernibility can 
result from a substantial reflectivity difference under low-light con- 
ditions or substantial illumination when reflectivity differences are 
small. Trailing cables, control valve handles, and machine protrusions 
should be illuminated such that an operator can see them. Visibility 
can be improved by changing the reflectivity of hazards and objects with 
paint or color pigmentation. An expeditious application of luminous 
rock dust to the work place has been suggested as an alternative to high 
power lighting. 

Some visibility problems result from the fact that the reflectivity of 
work place surfaces may vary as the mine is worked. Coal is a much 
poorer reflector than rock or rock dust. A high seam work place with 
all coal surfaces requires a substantial amount of illumination. Ap- 
propriate lights may seem to be brilliant when the seam becomes lower, 
the roof turns to rock, or the roof and ribs are rock dusted to prevent 
dust explosions. In Figure 3, appropriate shielding and luminaire dif- 
fusion improves operator visibility. Additional diffusion is placed on 
luminaires seen by the operator, nearby luminaires are shielded from 
view. The continuous miner lighting system shown may be adequate with- 
out shields in high seam or work places with coal roofs. The shielding 
allows the machine operator to see better in low seams with slate roofs. 

Field of view should be similarly illuminated . As discussed previously 
in the thin seam rope-propelled machine example, fields of view must be 
similarly illuminated for the workers' eyes to readily adjust. Machine 
operators working from a fixed position can be shielded from viewing 
luminaires. For others, adaptability is determined by the glare of 
direct view luminaires. Improved visibility can result from several 
glare reducing actions. 

• Mount the luminaires extremely low — below eye level. 

Use fixtures with lower power, bigger reflectors, and 
a large source area. 

Use two smaller luminaires to provide required light 
levels with less glare. 

Raise luminaire background illumination. 

Avoid placing lamps where workmen must look. 

Lower glare illumination systems can result from using several of 
these actions. 



223 



DIFUSSION • Min. • MAX. 



Black-Out Shield 
Length and Width 
of Cage 




Black-Out Shield 



FIGURE 3. - Methods of shielding and diffusing luminaires 




FIGURE 4. - Hinge mount provides access and integration. 



224 



Systems Provide Effective Long-Term Illumination 
When Future Illumination Needs Can Be Easily Met 

A mining machine is purchased with the expectation that it will work pres- 
ent and future coal reserves, but not necessarily in the same coal seam or 
state. Often, coal seams vary in height beyond the expectations of core drill 
samples. Illumination requirements change with the seam height and particu- 
larly with changes in the use of canopies. When a machine changes seams, or 
the seam height changes, light levels may have to increase or decrease, and 
shields may have to be added, moved, or extended. Additional luminaires or a 
different luminaire may be required because of canopy addition or deletion. 

Future work place conditions must be known . A better illumination 
system can result when the future use of the machine is known or 
projected. 

Future illumination system needs must be known . Future illumination 
needs can be identified from federal regulations, and proposals from 
the lighting manufacturers. 

Systems compatible with future illumination needs should be selected . 
Future needs can often be satisfied by providing additional lumi- 
naires or higher output illumination. Sometimes this is a problem. 
Additional luminaires may not be feasible in lower seams, particu- 
larly when they must be on top of the machine. Future needs should 
be met by simple modifications such as the addition of a fluorescent 
luminaire or the removal of one fluorescent and the addition of two 
sodium vapor headlamps. These types of modifications can be easily 
made if they were anticipated at the time of system selection. 

YOU COST EFFECTIVELY ILLUMINATE 
WHEN EXTRACTION LABOR COSTS ARE LOWER 

Labor costs for coal winning, coal loading, and roof bolting are a sub- 
stantial part of the extraction resource costs which the mine operator must 
control. Ideally, extraction labor costs would be lower because of work place 
improvements. The mine operator can expect lower extraction costs when the 
addition of lighting systems causes little production delay, and increases the 
productivity of coal winning, loading and roof bolting. 

Extraction Labor Costs Are Lower 
When Lighting Causes Few Production Delays 

A production delay idling two or four miners, and the extraction machine 
for one to three hours occurs when the explosion-proof integrity of a lumi- 
naire is not maintained, when a lamp failure results in a work stoppage, when 
the machine breaks because luminaire mounting prevented lubrication, or when 
a luminaire must be removed so a machine can move past a roof timber or work 
a tight rib position. 



225 



Fixtures must be protected against damage . Slate and other minor rock 
falls should not damage the explosion-proof construction of luminaires. 
An integrated design using rub rails or flush mounting should be used 
to prevent luminaires from rubbing against natural and man-made roof 
and rib protrusions. Guards, rub rails and flush mountings are much 
easier to provide when luminaires are small. 

Some lamp failure/work stoppages can be avoided . Loss of visibility 
should result in a work stoppage. This production loss can be reduced 
when long lamp life is realized. Lamps without filaments, or lamps 
which use strong, well supported filaments are desirable. Fluorescent 
lamps are more desirable than incandescent lamps. Rough service in- 
candescent fixtures should include spring mounts which absorb shock 
and rubber pads to damp vibrations. Burn-outs can be avoided by a 
preventive maintenance effort which prematurely replaces lamps. 

Hinged mounts and small luminaires prevent other delays . Access to 
maintenance points is more easily provided when luminaires are small. 
Also, an installer with some time and material can hinge mount fixtures 
to provide access as shown in Figure 4. MSHA has provided an S.T.E. 
modification program which allows the installer to move a fixture to a 
more favorable location when simple procedures are followed. Smaller 
fixtures, particularly smaller fluorescent fixtures, are desirable be- 
cause they would allow vertical mounting on the sides of machinery. 
Most fluorescent fixtures are at least 86 centimeters (34 inches) long 
and cannot be mounted vertically on most machines because only 45 to 70 
centimeters (18 to 28 inches) of space is available. 

Extraction Labor Costs Are Lower 
When Increased Productivity Results from Lighting 

Increased machine productivity can be expected as a result of supplemen- 
tal lighting, if the machine can be maneuvered more efficiently at full speed, 
and the operator is attentive to fundamental mining activities. 

Machine maneuvering is more efficient and full speed is utilized . When 
trailing cables, roof support timbers, co-workers, and the protruding 
edges and corners of machinery are readily seen, then the machine op- 
erator can more efficiently maneuver his machine and can realize the 
full speed capability of his equipment. These objects are readily seen 
when they are discernible from their surroundings. As mentioned earlier, 
discernibility results from either a substantial reflectivity difference 
under low light, or substantial illumination when reflectivity differ- 
ences are small. Shields and low glare illumination are necessary to 
the operator's productive use of machinery. 

The operators must be attentive to fundamental activities . Operators 
make productive use of machinery when they are attentive to the tasks 



226 



of machine position and other fundamental tasks such as coal cutting, 
loading, or roof bolting. The operators cannot be attentive when 
they are concerned about the vulnerability of luminaires, are shield- 
ing their eyes, or turning lighting systems off and on. A good light- 
ing system will eliminate operator need for these activities. 

YOU COST EFFECTIVELY ILLUMINATE 
WHEN MAINTENANCE LABOR COSTS ARE ABOUT THE SAME 

Coal mining machinery must be compact in order to work within narrow en- 
tries needed to stabilize the roof, and along variable height coal seams which 
follow undulating rock beds. Machinery with either redundant capabilities, or 
based on large design margins, are uncommon. Maintenance efforts are a sub- 
stantial part of a mechanized mining operation because the machinery is com- 
plex and because it has self-destructive capabilities. In providing machine 
illumination systems, the mine operator should hope to avoid an increase of 
his maintenance burden. Provided he is sure that the lighting systems are 
being used, he will know that maintenance costs have been held near previous 
cost levels when few service calls are made and when those calls generally re- 
quire only a modest labor effort. 

Maintenance Labor Costs Are About the Same 
When Lights Are Used and Maintenance Costs Are Low 

The costs of maintaining machinery with lighting systems are not known 
unless the machinery is working and the lights are used. When the machinery 
and lights are actively used, cost could blossom. An hour meter can estab- 
lish that lights are being used, but most operators must rely on the work of 
production supervisors and the knowledge that lamps are frequently replaced. 

Maintenance Labor Costs Are About the Same 
When Few Service Calls Are Made 

Maintenance labor costs are low when maintenance is seldom required. 
Few service calls will be made when the system operates reliably for an ex- 
tended time, or the production crew maintains the lighting systems. 

Reliable system operation results from the selection of a well 
developed illumination technology . Survival against shock and 
vibration, over-voltage spikes, rock falls and rib collisions 
results from the salient features of the selected lamp tech- 
nology and from the ability of the designers to compensate for 
shortcomings. Usually, the designers know the salient features, 
but are unsure of the requirements of the application. Over- 
design can be costly, but is often necessary where application 
data are unknown. 



227 

Maintenance by the production crew is possible when simple re- 
placement or preventive maintenance can be done during produc- 
tion delays . Production delays often average one hundred (100) 
or more minutes a shift. Idle operators or section mechanics 
may be able to maintain lighting systems when replacement fix- 
tures are on hand and can quickly be exchanged. Cheaper and 
smaller luminaires could make this possible. Figure 5 shows a 
small luminaire with a quick packing gland which should allow 
production crew maintenance. This luminaire, which is being 
developed under USBM Contract J0188077 by Booz, Allen, can 
easily be electrically disconnected. Once power has been re- 
moved from the machine, the grommet-type packing gland can be 
opened and the power connector pulled apart. This procedure re- 
quires little knowledge of the luminaire. The snap-on poly- 
carbonate guard and diffuser can also be quickly cleaned or re- 
placed by production personnel. Hopefully, high volume produc- 
tion will allow these replacements to be economically stored at 
each work place machine. 

Maintenance Labor Costs Are About the Same 
When Outside Maintenance Can Service Systems Quickly 

When parts are stored in a warehouse outside the mine, or when technical 
knowledge is necessary to a repair, then outside maintenance labor is required. 
Figure 6 shows some of the obstacles which must be overcome before outside 
maintenance can repair work place machinery. Obviously, low maintenance costs 
are a result of avoiding obstacles. 

As shown in Figure 6, the work crew must accurately diagnose the problem, 
walk to the mine phone and accurately communicate their findings. The out- 
side mechanic must understand that communication, find the right tools and 
parts, and bring them to the work site - usually about 4 kilometers (2.5 miles) 
from the warehouse. The mechanic must find a vehicle to transport him and se- 
cure a right-of-way to the section. For various reasons, the mechanic arrives 
late and does not have one essential part or tool. Consequently, that need 
must be phoned to the warehouse and the part, another vehicle, and a driver 
must be found before the part is on its way. 

Obviously, outside maintenance is inherently slow. Since an outside serv- 
ice call is slow, and is generally coincident with a production delay, outside 
maintenance should be avoided wherever possible. When it can't be avoided, a 
production worker should be able to quickly and accurately diagnose the cause 
of the problem, the parts which should be replaced, and the tools necessary 
for replacement. Outside mechanics should quickly make replacements and re- 
turn the machinery to production. 

Production crews should be able to quickly and accurately diagnose 
lighting problems . Since inside parts and system operation is not 
readily understood, lamp signals (neons or LEDs) should be provided 



228 



PACKING 
GLAND 



FEMALE 
CONNECTOR 



HOSE 
CLAMP 



CONDUIT 
HOSE 




ELECTRIC 
CABLE 



SNAP ON 
GUARD /DIFFUSSER 



REPLACEABLE 
FIXTURE 



FIGURE 5. - Short, small X-sectlon, quickly serviced luminaire. 



pHONE 




■+- 



SYSTEM 



HAULAGEWAY 




There is supposed 

to be a MAINTENANCE JEEP 



FIGURE 6. - Obstacles to maintaining machinery. 



229 



which can pinpoint modules (luminaires, or power modules) which 
should be replaced. For example, when luminaires are powered in 
series, a lamp failure will cause the whole series to fail. With- 
out a lamp signal to pinpoint the cause, the problem could be in- 
accurately diagnosed as any one of the luminaires or the power 
system module (ballast) which controls the series. Substantial 
time and costs could be incurred, should the wrong modules be 
serviced first. 

Maintenance should quickly replace failed modules . Modules, such 
as luminaires and ballasts, can be tested and diagnosed. Quick 
repairs are possible when good parts can be quickly exchanged for 
bad parts. Additional production and maintenance costs can be 
avoided when repair risks are reduced. Luminaires and power 
modules should be designed for quick exchange. Repairs should 
not be attempted when quick exchange with good parts is feasible. 
Mine operators might expect lighting systems' manufacturers to 
provide tested modules with compatible interface connections. 

YOU COST EFFECTIVELY ILLUMINATE 
WHEN MACHINERY RENEWAL COSTS ARE ABOUT THE SAME 

Machinery has made mining more safe and productive. The abusive extrac- 
tion process gradually destroys components which are necessary to the survival 
of mining machinery. The modern mechanized mining operation is dependent on 
many machines which must be maintained and periodically renewed. The extra 
parts or renewal parts necessary for machine maintenance and renewal are pro- 
vided by ongoing renewal parts budgets. Production machinery modifications 
such as the addition of supplementary lighting systems and operator canopies, 
are provided as part of this budget. The renewal parts budget must incur the 
costs of providing new lighting systems, but over the long-term, the cost of 
providing lighting systems and parts should be a small part of the costs for 
machinery renewal. This can happen when the costs for renewal lighting parts 
is low, and the distributed costs of purchasing and installing lighting sys- 
tems is low. 

Machinery Renewal Costs Are About the Same 
When Lighting Renewal Part Costs Are Low 

Machinery renewal part costs cannot be low unless the costs for lighting 
renewal parts are low. For these to be low, lighting repair parts should be 
infrequently needed or they should be inexpensive. 

Renewal lighting parts should be infrequently required . As discussed 
earlier, lighting renewal parts will be needed whenever the system 
fails to operate or the explosion-proof integrity has been damaged. 
These failures are avoided and renewal costs are lower when a reliable 
illumination system with durable and integrateable luminaires are 
selected. 



230 



Renewal lighting parts should be inexpensive . When luminaires must be 
mounted in vulnerable positions, or mine power irregularity prevents a 
lighting system from being totally reliable, then a lighting system 
with inexpensive renewal part costs is desirable. Original costs and 
renewal costs are dependent on how efficiently a manufacturer is able 
to focus development, manufacturing, sales, and product support efforts 
on the ultimate solution to mine lighting needs — i.e., a competitively 
attractive product which is economical to operate and readily available. 

Low development effort . A technology can be inherently expensive 
to develop into useful products when salient features must be 
supplemented to satisfy application requirements. D.C. lighting 
systems which rely on inverters which make high frequency alter- 
nating current, and intrinsically safe systems (cannot ignite 
methane) which must limit voltage and current, are much more 
difficult to develop than basic ballast or across-the-line 
lighting systems. Glass lense luminaires withstand higher op- 
erating temperatures than do plastic lenses. Small luminaires 
with tubular globes are much easier to develop, than large 
luminaires with several windows. 

In developing low-cost luminaires, designers must strive to 
identify solutions which best utilize salient features of 
materials and technologies. 

Low unit manufacturing requirements . The manufacturing cost of a 
product is reduced when the productive advantages of manufacturing 
processes can be used to replace manual labor. Casting, extrusion, 
injection molding, stamping, forming, and drawing processes make 
parts in volume and eliminate manufacturing steps and associated 
handling, setup, and run requirements. Automation can also reduce 
costs. High part volumes are not necessary to take advantage of 
work center manufacturing. Numerically controlled turning centers 
and milling centers save setup, handling, and run times. Designers 
must take advantage of manufacturing technologies in their product 
designs in order for manufacturing costs to be low. Production 
volumes have a major impact on cost and design as they determine 
affordable tooling and special automation. Product volumes are 
highest when the development effort results in a clearly superior 
product which drives off inferior competition. 

Low application effort supports sales . Product costs include 
application engineering which is necessary to sell products. 
Many lighting sales are predicted on a prior-to-installation 
approval from MSHA, i.e., the system meets federal requirements. 
The manufacturer must model a machine, arrange luminaires, con- 
duct photometric studies, process a MSHA application, and obtain 
a MSHA Statement of Test and Evaluation (S.T.E.). This process 
raises product costs whenever an unfeasible or unattractive 



231 

lighting system results. Efficient lighting system design re- 
quires accurate knowledge of mechanized machines and their op- 
eration, as well as knowledge of lighting product capabilities, 
and federal and state illumination system regulations. 

• Low customer support requirements . A manufacturer must have sales, 
distribution, and service staffs and warehouses. Product costs 
are lower when significant expansion of staffs and services is 
avoided. Manufacturers which are adding a product to other lines 
sold, distributed, and serviced in the mining areas, should have 
more economical products. 

Machinery Renewal Costs Are About the Same 
When Distributed Purchase and Retrofit Costs Are Low 

A lighting system with six to eight fixtures, priced at $400 to $800 per 
fixture, and requiring 60 to 200 manhours of retrofit installation, is not in- 
expensive — particularly when retrofitted to a small machine such as a single 
head roof bolter which is worth only $18,000 to $28,000 new. Obviously, the 
costs for mechanized machinery are substantially increased unless this $4,000 
to $11,000 investment can serve the machine for several years. Machinery re- 
newal costs are lowest when lighting systems are purchased and installed at a 
low cost and these original products satisfy the mine operations needs for a 
long time. 

Low purchase and retrofit costs are desirable . Original system purchase 
is usually inexpensive when renewal parts are inexpensive. We have seen 
that this results from efficient development, manufacturing, application 
engineering, and customer support efforts which result in competitively 
attractive products that are economical to operate and readily available. 

Low installation costs result when all the mounting materials are provided, 
the installation instructions are clear and comprehensive, and the instal- 
lation effort is small. 

All materials are provided . Most manufacturers provide universal 
brackets for mounting luminaires in common orientations. Hinged 
and latched mounts and rub rails are not provided because specific 
machine (not model) knowledge is required. These mounts and guards 
often would not be needed were luminaires substantially smaller. 
Some improvements could result if illumination manufacturers made 
appropriate hinges, latches and basic rub rail designs available. 

Clear installation instructions should be provided . Manufacturers 
generally supply installers rather than installation instructions. 
Some installation instructions are found on approval drawings. 
These usually are confusing because they provide more product in- 
formation than an installer needs. Dimensioned or scaleable in- 
stallation drawings can show discrepancies between the designers 



232 



expectation of the host machine and the actual machine. These 
discrepancies often result in installation problems (particu- 
larly where a S.T.E. does not allow luminaire relocation). 
Unproductive and costly installation efforts can be avoided 
when a proposed system is clearly applicable. An operator 
should examine the proposal before installation is started. 

Installation effort is small . The installation effort is small 
when the S.T.E. is clearly appropriate without relocating lamps, 
and when alternate mounts and guards do not have to be designed 
by installers. Small luminaires allow mounts and guards which 
are much more economical to fabricate and install. 

Long-life systems are desirable . Purchase and retrofit costs can be 
insignificant when they can be distributed among several years of equip- 
ment operation; consequently, a longer system life is desirable. A long 
system life is realized when premature failure and premature rework is 
avoided. 

Premature failure is avoided . Original lighting systems will, 
for the most part, survive provided a reliable power system was 
selected and the luminaires were mounted integral with the ma- 
chine or protected by substantial rub rails. 

Premature rework is avoided . Low distributed purchase costs are 
not realized when a system is replaced prematurely with an alter- 
native system. As a result, rework can be justified only when 
other savings offset the cost of a second purchase and instal- 
lation. Since purchase and installation costs are sizeable, 
rework is to be avoided. In selecting an economical lighting 
system, a mine operator must be sure that all feasible tech- 
nologies and configurations were evaluated, developed, and 
selected. 

All feasible systems were evaluated . Feasible systems are 
not always identified or evaluated. As seen with incandescent 
systems, false assumptions may prevent consideration of some 
technologies. Other alternatives are not developed because 
manufacturers have limited development capital and other 
product interests. 

Hybrid systems using products from several manufacturers 
may be economically desirable. A simple example is the 
hybrid lighting system shown in Figure 7, for a Long Airdox 
roof bolter. This system uses fluorescent fixtures from one 
manufacturer, with a sodium vapor luminaire from another. 
This hybrid system allowed Booz, Allen to illuminate a small 
machine with only four luminaires. The sodium fixture is 



233 

also a hybrid as Booz, Allen, not the manufacturer, 
provided the external cage mounted diffuser shown in 
Figure 8. Although sodium vapor fixtures are marketed 
by two manufacturers, only one had a luminaire suited to 
this application. A third manufacturer was the source 
of the fluorescent luminaire. From this example, you can 
see that the manufacturer who does not have a full line of 
products cannot recommend a hybrid system. Consequently, 
hybrid systems have to be investigated by the potential 
buyer or someone else. 

- Most economical solution was developed and selected . Ma- 
chinery renewal costs are low when lighting systems are not 
prematurely replaced. Lighting systems will not be reworked 
when new solutions are developed. A mine operator will not 
be faced with expensive, and often repetitive, rework pro- 
grams when he has taken an active role in avoiding evolution- 
ary obsolescence. He must participate in efforts to rapidly 
develop ultimate lighting solutions — competitively attractive 
products which are economical to operate and destined to be 
available for a long time to come. 

SUMMARY OF REQUIREMENTS AND RECOMMENDATIONS 
FOR COST EFFECTIVE ILLUMINATION 

The general requirements for cost effective illumination developed in this 
paper are summarized in Figures 9 and 10. More economical mine lighting can 
be expected when and if new products can satisfy more of the many requirements. 
Most notably, there is a need for: 

Shorter, smaller cross section luminaires. 

Quickly replaceable fixtures using machine stored spares. 

Quick identification and development of clearly economical 
lighting systems which avoid excessive rework. 

Improved capability to discern hazards and objects from 
surroundings. 

Low glare luminaires. 

Because coal industry segments have different types of equipment and 
working conditions which present different types of problems, general answers 
are of limited value. This paper was intended as a baseline for developing a 
collective agreement between the manufacturers and users of mine lighting sys- 
tems as they focus on the technical and economic needs of the industry. It is 
hoped, that from this start, the following efforts will continue. 



234 



SODIUM VAPOR 

LUMINAIRE 




FLUORESCENT 
LUMINAIRE 



Larfeir! 



**tt*w&it*>yv 



SMALL 
LONG AIRDOX 
ROOF BOLTER 

FIGURE 7. - Hybrid lighting system from three manufacturers, 




TRANSLUCENT 
POLYCARBONATE 
DIFFUSER 



DIFFUSER GUIDE 
WELDED TO STANDARD 
GAGE GUARD 



STANDARD CONTROL PRODUCTS 14312D 
MACHINE LIGHT 



FIGURE 8. - Hybrid luminaire 



235 



SAFE UCHTIMG 
SYSTEMS ARE USED 



SYSTEMS PROVIDE 

EFFECTIVE LONG TERM 

ILLUMINATION 



-• SAFE DESICN 
IS USED 



MSHA SAYS 



IT'S SAFE 



STATE BOM 
SAYS IT'S SAFE 



SYSTEM IS PER 
APPROVED DESIGN 



LIGHTS OPERATE 
-• UNDER EXPECTED 
CONDITIONS 



OPERATOR SEES 
BETTER 



FUTURE NEEDS 
CAN BE EASILY MET 



-• SPARKS DO NOT IGNITE METHANE 
-• COAL DUST IGNITION PREVENTED 



-• HICH VOLT ACE SHOCK AVOIDED 

-• NO EXPOSURE TO HOT OR MOVING PARTS 



-• MSHA CERTIFIES ENCLOSURES 



-• MSHA APPROVES MACHINE/SYSTEMS 



-• MSHA INSPECTS ILLUMINATION 
-• MSHA GIVES S .T . E . APPROVAL 



-• STATE APPROVES MACHINE 



-• STATE INSPECTS MACHINE 

-• SYSTEM BUILT TO APPROVED SPECS 



-• SYSTEM IS MAINTAINED AS APPROVED 



-• LAMPS RESTART ON LOW VOLT ACE 



-• D.C. SYSTEMS OPERATE ON HICH VOLTAGE 



-• D.C. SYSTEMS SURVIVE TRANSIENT SPIKES 



-• HAZARDS/OBJECTS ARE DISCERNABLE 



-• FIELDS ARE SIMILARLY ILLUMINATED 
-• FUTURE CONDITIONS KNOWN 



-• FUTURE EQUIPMENT NEED KNOWN 



-• COMPATIBLE SYSTEM SELECTED 



FIGURE 9. - Cost effectiveness tree - application branches 



EXTRACTION LABOR 
COSTS ARE LOWER 



LITTLE PRODUCTION 
-• DELAY RESULTS 
FROM LIGHTING 



INCREASED MACHINE 
PRODUCTIVITY RESULTS 



FIXTURES ARE PROTECTED 



-• LAMP FAILURE/WORK STOPPACE AVOIDED 



c 



-• MOUNT ALLOWS ACCESS 

-• REMOVAL IS NOT NECESSARY TO OPERATION 



• MANEUVERING IS FASTER 

OPERATOR IS ATTENTIVE TO FUNDAMENTAL ACTIVITY 



MAINTENANCE LABOR 
COSTS ARE SAME 



FEW SERVICE 
CALLS ARE MADE 



OUTSIDE MAINTENANCE 
MAKES QUICK REPAIR 



c 



SYSTEM OPERATES RELIABLY 
PRODUCTION CREW MAINTAINS W/O DELAY 



-• PRODUCTION CREW ACCURATELY DIAGNOSE 



MAINTENANCE REPLACES FAILED MODULES 



MACHINERY RENEWAL 
COSTS ARE SAME 



LOW LICHTING 
RENEWAL COSTS 



LOW DISTRIBUTED 

PURCHASE AND 
RETROFIT COSTS. 



c 



• RENEWAL PARTS INFREQUENTLY REQUIRED 
RENEWAL PARTS INEXPENSIVE 



c 



LOW PURCHASE AND RETROFIT COST 
INSTALLED SYSTEMS LAST 



FIGURE 10. 



Cost effectiveness tree - economic branches. 



236 



• Manufacturers and mine operators can agree on the general 
requirements for cost-effectively illuminating work places. 

• Specific systems addressing the specific needs of diverse 
market segments are developed. 

• Specific recommendations can be collected into a master plan 
for the development of better mine lighting systems. 

Designs which largely satisfy technical and economic objectives can be 
expected if the industry is prepared to take a systematic approach to obtain- 
ing and weighting the importance of the many subordinate requirements and to 
using these to develop better lighting systems. 



237 



TITLE OF PAPER: Coal Industry Experience with 
Mine Illumination Systems: 
Maintenance Requirements and 
Personnel Acceptance 

AUTHOR: Mr. Jon Yingling 
Project Engineer 
Bituminous Coal Research, Inc. 
Monroeville, Pennsylvania 



Mr. Yingling, a graduate of Pennsylvania State University, with a B.S. 
degree in Mining Engineering, is a Project Engineer at BCR, where he has 
worked since graduating in 1978. He has been involved in projects in under- 
ground coal mine illumination, respirable dust control, and industry- training 
needs. 

Mine lighting experience includes field survey investigating lighting 
maintenance requirements, installation problems, personnel acceptance, 
status of hardware development, and status of factory integration of systems 
on face machines . 



238 



COAL INDUSTRY EXPERIENCE WITH MINE ILLUMINATION SYSTEMS 
MAINTENANCE REOUIREMENTS AND PERSONNEL ACCEPTANCE 

by 
Jon C. Yingling 1 



ABSTRACT 

This paper discusses maintenance requirements of illumination systems in 
coal mines and personnel acceptance of such systems installed on longwalls and 
room- and-pi liar machines. Specific subtopics addressed are as follows: 
magnitude of maintenance requirements, mechanical damage, lamp life, electri- 
cal failures, electrical troubleshooting, acceptance ratios, frequency of 
particular acceptance problems, and equipment operators' suggestions for 
lighting improvements. 

BACKGROUND 

2 
Under a research program sponsored by the U.S. Bureau of Mines, 

Bituminous Coal Research, Inc., (BCR) conducted interviews with safety, 
maintenance, and operating personnel at 60 underground coal mines to assess 
their experience with illumination systems. The two primary goals of the 
interviews were to: (1) establish a definition of major installation, mainte- 
nance, and personnel-acceptance problem areas to assist the Bureau and other 
involved parties in determining research and development needs; and (2) to 
determine successful approaches and techniques for implementing mine lighting 
in order to establish installation and maintenance guidelines for industry 
use. This paper is based on the' findings of this study. 

MAINTENANCE REOUIREMENTS 

Lighting-maintenance requirements, in terms of system-reliability levels, 
repair costs, and production losses due to machine downtime, depend on the 
system's capability to meet the often extreme mechanical and electrical per- 
formance requirements of mine application and on the difficulty of identifying 
faults and making repairs when system failures do occur. The discussion below 
addresses the magnitude and nature of these requirements and approaches which 
show promise in minimizing them. 



project Engineer, Bituminous Coal Research, Inc., Monroeville, PA 

2 Contract JO308040 "Development of Guidelines for Installation and Maintenance 
of Mine Illumination Systems"Magnitude of Requirements 



239 

Figure 1 shows component-life data on lamps, luminaires, and core-and- 
coil ballasts which were calculated from inventory-depletion records provided 
by a number of the studied mines. Table 1 shows the percentage distribution 
of these mines which realized component service lives of less than 1 year, 
from 1 to 3 years, and greater than 3 years. These data apply strictly to 
lighting applications on ac-powered, room-and-pillar , face machines. Scoops 
and shuttle cars, also included, are both ac and dc . 

The data show a surprisingly wide range of realized service lives among 
the represented mines and an uneven distribution of the population across this 
range, which is believed to be indicative of a large variability in magnitude 
of lighting-maintenance requirements from mine to mine. Mine conditions, 
characteristics of the utilized hardware in view of these conditions, and the 
protective measures taken upon system installation greatly affect the rate of 
lighting hardware failures. Various problems can be quite significant at a 
given mine, but no problems are consistently severe. As shown in Table 1, the 
majority of mines are realizing component lives in the higher ranges; but, 
also, a significant minority are replacing components, particularly lumi- 
naires, on an annual basis or sooner. 

Limited data were available on machine downtime. Table 2 shows total 
lighting delay-hours during 1980 for one large company which operates approxi- 
mately 175 room-and-pillar sections and 13 longwalls. Conversion of these 
figures into lost production costs is a controversial issue, but many mines 
assume a cost of $15 to $25 per minute of continuous-miner downtime and ap- 
proximately $100 per minute of longwall downtime. 

Except for these downtime figures, no statistical data were obtained on 
longwall-maintenance requirements. Although there were exceptions, most 
company representatives felt that maintenance requirements on longwalls were 
low or moderate, significantly less than on room-and-pillar applications. 

Mechanical Damage of Components 

Equipment structure and photometric requisites dictate some degree of 
exposure of machine-mounted lighting components to external impacts, which may 
result in their damage. On room-and-pillar machines, such damage is the most 
significant lighting-maintenance problem, although its magnitude varies from 
mine to mine. Approaches to minimize this damage include modification of 
machine structure to integrate the lighting fixtures, provision for supple- 
mentary external guards, utilization of stronger hardware, and movement of 
fixtures away from vulnerable locations. 

Integration of most or all lighting components into machine profile, via 
recessing, while concurrently meeting photometric requisites has been shown, 
in formal demonstration projects, to be technically feasible and effective in 
reducing levels of mechanical damage. Unfortunately, this technology has not 
seen widespread implementation in the field. Many operators do not believe 
integration would be cost effective under their particular conditions 



240 



A. LAMPS 






flUORESCEHT 

INCANDESCENT 

H.I.P. 




MEAN PERIOD UNTIL REPLACEMENT, 
HUNDREDS MACHINE SHIfTS 



8. LUMIN AIRES 



10 



£ 


8- 




*• 












* 


6 




>*. 






<5> 


t 




"S. 




* 


2 





■1 FLUORESCENT 
I I INCANDESCENT/ H.I. D. 
HEADLIGHT HOUSINGS 




0-2 



4-6 8-10 15-20 
2-4 6-8 10-15 >20 

MEAN PERIOD UNTIL REPLACEMEHT, 

HUNDREDS MACHIHE SHIfTS 



N.f. 



C. BALLASTS 

ICORl AND COIL) 



■B fLUORlSClNT 

ma h.i.b. 




0-5 10-IS >20 " N.f.* 
5-10 15-10 
MIAH PfRIOD UNTIL RtPLACCMCNT, 
HUNDREDS MACHINl SHIfTS 

N.f. - No failures of this type component were recorded during 
period covered by inventory depletion data. 



FIGURE 1. - Distribution of mean component service life values, 



241 



TABLE 1 . - Percentage distribution of mines by 
realized component service life 



Component 

Flourescent luminaires 

HID/incadescent luminaires** 

Headlight housings , 

Fluorescent ballasts 

HID ballasts 



Percent mines realizing component 
service lives: 



<1 year* 1-3 years* >3 years* 




*at 675 machine-shifts per year 
**4 mines only 



22 


48 
50 
78 



TABLE 2. - 1980 lighting downtime at one large company* 





Application 


Delay hours 




1224 




633 




302 


Shuttle cars 


1586 


Longwall 
- Face 


85 




20 



*175 room and pillar sections 
13 longwall s 



242 

(especially in high coal). Others cite that technical reasons have inhibited 
activity in this area, including (l) uniqueness of machine structure to each 
model-type or, in many cases, each individual machine; (2) impract icality of 
making machine modifications to accommodate fixtures in some areas; and 
(3) uncertainty about maintaining photometrical compliance if modifications 
were made . 

In retrofit/rebuild installations, most recessing activity has been on a 
"spot" basis, where modifications have been relatively easy and a major need 
existed. For example, on the continuous miner shown in Figure 2, the lumi- 
naires on the machine offside had to be side-mounted because of clearance 
problems. However, when side-mounted, they were not visible to the machine 
operator and were being ribbed repeatedly. The illustrated recessing was 
accomplished by modifying the coverplate structure and making minor machine- 
component relocations. Recessing was not attempted on the operator's side 
because the fixtures were visible to the operator and, hence, he was less 
likely to rib them. Moreover, recessing here would be more difficult due to 
the presence of the controller box. Exchange of machine-model-specific infor- 
mation on feasible recessing locations, and necessary machine modifications, 
and assistance in predetermining photometric impact of particular recessing 
applications could facilitate progress in integration of retrofit lighting- 
systems . 

Another approach, which is more frequently applied than recessing, is the 
use of supplementary guards, such as bumpers and siderails, to protect the 
luminaires. These guards have been especially useful on applications of high- 
profile luminaires in low coal, as illustrated in Figure 3. However, diffi- 
culty in finding suitable anchor points for the guards may make installation 
difficult on some applications. Moreover, the guards are not universally 
effective; for instance, a high-profile fixture protruding from the side of a 
continuous miner can be frequently damaged despite the use of substantial 
guards . 

By far, the most common approach taken by the mines to improve durability 
is the selection of hardware which, because of its design, can better with- 
stand the forces to which it may be subjected. Many mines have discontinued 
use of fluorescent luminaires and now utilize H. I .D ./incandescent fixtures 
because of their generally more substantial construction. Although the change 
has frequently proven beneficial, lamp housings on many fixtures are so strong 
that the luminaire can be driven into the machine by some impacts, causing 
significant damage to underlying components. Also, in low coal, where poten- 
tial for roofing and ribbing is generally highest, the high profile of these 
fixtures limits their application. Protective cage construction is of great 
importance to the durability of fluorescent fixtures. Many mines have re- 
ported large reductions in damage frequency when they use the "heavy-duty" 
cages offered by manufacturers in recent years. For durability, the cage 
should be constructed of strong members, and it is best if the mechanical 



243 




FIGURE 2. - Retrofit recessing of luminaires on low-coal miner. 



244 




FIGURE 3. - Supplemental guards have facilitated use of high-profile 
luminaires on low-coal machines. 



245 

connection between the cage and luminaire end housings is weak, minimizing 
stress transfer. Mounting feet should be given great consideration in selec- 
tion of headlight housings. Thin, aluminum feet are especially prone to 
breaking and may be difficult to repair. Fixtures are now available with 
replaceable feet, and field experience with these has been favorable. 

Luminaires should be viewed as salvagable items. Damage frequency, 
extent of damage, and repair costs should be collectively considered in 
evaluating their durability. Service companies have reported that a 3-to-l 
cost differential may exist in average repair costs between competitive lumi- 
naires, dependent on materials of construction, design, and parts markup. 

At a number of mines, cable damage was reported to be the major cause of 
lighting downtime. This was attributable not only to the frequency of failure 
incidents, but to the often excessive times for making repairs. For example, 
mean downtime for cable replacements on shuttle cars at one mine was over four 
hours. In most cases, these difficulties can be avoided by careful planning 
of cable runs. Cables should be routed under machine covers wherever possible 
and points where the cable could be pinched if the covers are bent should be 
avoided. Inverted angle iron or pipes might be used for protection where top 
deck or boom runs are necessary. Sufficient slack should be left at articula- 
tion points to avoid fatigue damage. Exposure of cables between the machine 
body and the luminaire should be minimized through proper routing and selec- 
tion of appropriate gland orientation (available hardware often places limita- 
tions on this aspect). On roof bolters, cables are often damaged by the 
throwing of supplies on the top deck. Compartments should be provided to 
facilitate orderly arrangement of supplies in the presence of luminaires and 
cables. Cable changes are often time-consuming because of the difficult paths 
through which they must be routed. On some runs, excessive change times can 
be avoided through installation of J-boxes at strategic locations (for exam- 
ple, on the luminaire side of conveyor crossover-channels) which eliminate the 
need to reinstall the entire length of cable in the event of failure. 

Mine lighting has resulted in a significant increase in application of 
X/P packing glands in locations where they are subject to damage. Glands are 
often damaged from slate fall to the exclusion of significant luminaire 
damage. Experience has been worse with tubing-style glands than with cast, 
clamp-style glands. Tubing glands are more easily deformed and the cable is 
more readily pulled through the sleeve. 

Gland guards have been applied with mixed results. Frequently, they are 
structurally under-designed and, as a result, are merely pushed into the gland 
when impacted. Figure 4 illustrates some successful designs. Care should be 
taken to insure adequate provision of space for inspection and servicing. 
Often it is good to mount the guard structure a short distance away from the 
gland. At this location, it will break the fall of the rock, but, if bent, it 
will not be forced into the gland. Machine operators tend to use the cable 
feeding canopy-mounted luminaires as a handhold for exiting the cab, pulling 
it from the gland. A handle might be installed for the machine operators on 
the canopy structure to eliminate this tendency. 



246 




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247 

The level of mechanical damage on longwalls is significantly lower than 
on room-and-pillar applications, particularly with respect to luminaires. On 
most faces it has been possible to locate the fixtures on the canopy (i.e., 
roof bar) structure, above the walkway or cable trough, where they are subject 
to few hazards. Face shooting may cause some damage if luminaires are left in 
place . 

A serious problem on a number of longwalls is the frequent incidence of 
cable damage. Extreme care is warranted in cable routing. Pinch points 
should be avoided. Sufficient slack should be alotted to permit staggered 
support advancement, but excessive slack may result in the cable's becoming 
exposed to the gob or riding under the support base. Slack must also permit 
the cable to clear, rather than snag on rock accumulated between the supports 
(especially on chock faces). Cabling requirements vary significantly among 
the different manufacturers' systems and should be given much consideration in 
selection of hardware. It may be advantageous to install the system on only a 
portion of the face (e.g., install only a single power supply or distribution 
box and associated luminaires) to determine optimum cable routing from 
experience before wiring in the entire face. 

Lamp Life 

The study results imply that lamp failure rates are often significant. 
The primary factors which contribute to premature lamp failure on mine appli- 
cations are machine vibration/shock levels, and over-/under-voltage drive. 
Reduced lamp life is most significant on shuttle-car applications where 
resultant downtime from lamp failures may approach the magnitude of lighting 
downtime from all causes on continuous miners or other face machines. Also, 
replacement costs may be significant when H.I.D. or VHO/SHO fluorescent lamps 
are used or where repair companies are utilized to make lamp replacements, 
even though they do perform other maintenance services. 

Several mines reported extreme life problems with HID (particularly with 
par-38 high-pressure sodium) lamps. One mine realized an average of only 16 
shifts from mercury-vapor lamps, while another 14-mine company realized an 
average of only 72 shifts from high-pressure-sodium lamps (rated life of these 
lamps may exceed 10,000 hours). No particular cause of these life problems 
could be identified nor was the trend consistent; many mines reported excel- 
lent life performance from the same type of lamps in similar applications. 
From the scarce evidence that was obtained, it appears that both voltage 
regulation and mechanical factors might cause the problems. 

Machine vibration/ shock levels can have a significant effect on lamp 
life. Many mines reported high failure rates in conjunction with rough 
shuttle-car runways or when continuous miners were cutting rock. Also, both 
fluorescent and incandescent lamps occasionally fail from mechanical shock 
when workers pound, or rock falls, in the vicinity of the luminaire. Low- 
voltage incandescent lamps have larger diameter filaments than their high- 



248 

voltage counterparts, which increases resistance to breaking from shock/ 
vibration. On shuttle cars, 60 percent of mines using 32 v or lower lamps 
reported satisfactory lamp life, while only 25 percent of those using higher 
voltage lamps reported satisfactory life. Incandescent lamps, regardless of 
voltage, should employ rough-service (RS) filaments. It should be noted that 
some headlight enclosures in use are approved for only 70-watt incandescent 
lamps; however, this size lamp is not available with rough service filaments. 
Finally, shock-dampening features, incorporated into design of the luminaire 
or in the luminaire mount, have been shown, in some cases, to reduce the level 
of lamp failures. 

On dc shuttle cars, where resistors are used to drop voltage to the 
proper level for incandescent headlights, lamp-life problems may result if the 
lamps are wired parallel with each other, but in series with the drop resistor 
(parallel circuit, Figure 5). This circuit was employed on many early appli- 
cations because of ease of installation. However, if one lamp burns out, 
circuit resistance increases, voltage drop across the resistor decreases, and 
the remaining operating lamp is overdriven, significantly reducing its life, 
unless the failed lamp is quickly replaced. Other wiring configurations can 
be used to eliminate this problem, but there are operational or installation 
problems associated with these. They are shown in Figure 5, with a discussion 
of relative advantages. Over 80 percent of mines employing the parallel 
configuration reported major lamp-life problems, whereas only 20 to 30 percent 
of mines using the other configurations reported major problems. 

On longwall applications, the Shockwave from face shooting frequently 
results in lamp failure, even without significantly damaging the luminaires. 
Although takedown or guarding in the blast zone is permitted under federal law 
(Section 75, 1719-2(f) CFR) , takedown is recommended in cases where face 
shooting is frequent. Use of a quick-release mounting technique on connector- 
equipped systems simplifies takedown. Under-voltage-related lamp failures may 
also be a problem on longwalls. Care should be taken to assure that line 
losses are not excessive and voltage is being maintained the length of the 
face . 

Electrical Failures 

Several factors have been identified which can result in significant 
electrical reliability problems on both ac and dc machine applications. Poor 
voltage regulation is perhaps the most important of these. A variable 
lighting-system supply-voltage can be detrimental to life of all electrical 
components in the system. One mine, which reportedly experiences up to 
25 percent voltage variation at the machine from a nominal 480 vac supply, 
receives the following mean service lives from system electrical components: 



249 



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250 

Mean service life, 
machine shifts 

Transformers 136 

Fluorescent ballasts... 104 

Mercury-vapor ballasts. 132 

Fluorescent lamps 74 

Mercury-vapor lamps.... 16 

Replacement cost of these components is $4,865 per machine per year. Ballasts 
differ in their sensitivity to voltage variations. Care should be taken to 
insure they are compatible to the actual operating voltage range on the 
machine. Under extreme operating voltage ranges, incandescent systems might 
be most appropriate. 

In addition to heat-induced failures of ballasts from overvoltage drive, 
other conditions have resulted in significant rates of failure of core-and- 
coil ballasts. Improper wiring connections accounted for some ballast fail- 
ures, particularly on 6-lead or multi-tap units, but experience has helped to 
minimize this problem. A number of operators expressed the sentiment that 
some manufacturers have done an inadequate job of heat-sinking or have 
increased the potential for heat-related failure by using poor ballast 
packaging arrangements. (For example, operators reported higher failure rates 
of those particular ballasts which are surrounded by other ballasts.) A very 
significant number of mines reported that the mounts which secure ballasts 
within the enclosure are subject to frequent mechanical breakage, which frees 
the ballasts and permits shorting. Finally, a large number of mines reported 
frequent, short-induced ballast failures. The tendency of ballasts to over- 
heat when lamp leads are shorted depends on design. Because of the high 
incidence of cable damage at some mines, these rates can be extreme. One mine 
using a new fluorescent ballast design, which drives two lamps in parallel, 
reported making 250 replacements over a matter of months, largely due to 
shorting incidents. 

Transformers were generally a non-troublesome electrical component. 
However, a surprising number of mines did report the experience of exceeding 
transformer kva capacity when additional headlights were added beyond STE 
specification to increase face lighting on continuous miners. Operators 
should check to see that the existing transformer has the necessary capacity 
before adding headlights. Also, on low-voltage lamp additions, conductor 
losses should be considered. 

Identification of failure causes on intrinsically safe systems on ac 
applications proved more difficult because of increased complexity and lack of 
diagnostic effort at the mines. Voltage regulation, moisture, and vibration- 
induced failures were reported. No significant reliability difference between 



251 

these systems and the simpler, conventionally-ballasted X/P systems was indi- 
cated . 

Application of power-conditioning systems on dc is much more difficult 
because of (1) variability of supply voltage over a much wider range than a 
typical ac application and (2) frequent high-voltage transients. Our findings 
(excluding incandescent systems) indicate: 

(1) Power parameters and, hence, reliability of system performance have 
been difficult to predetermine prior to installation. Manufacturers 
are frequently "custom tuning" their systems to local conditions on 
a trial-and-error basis. 

(2) All investigated systems applied where mine distribution was dc 
(e.g., trolley line, dc cable) experienced severe reliability 
problems. Conversely, many successful applications were found where 
mine distribution was ac and the dc originated at a load-center- 
based rectifier. 

(3) Some failures could be avoided if operators always turned the 
systems off during low load periods (e.g., during crew changes) when 
voltage tends to rise. 

No major electrical problems were identified for incandescent applica- 
tions on ac or dc machines. Because of low cost; simplified installation, 
troubleshooting, and repair; better operation and less damage under fluctu- 
ating voltage conditions; and a change in enforcement policy which facilitates 
use of lower output lamps on face machines, these systems have considerable 
popularity among mine operators and are seeing increased application on both 
ac and dc machines in both low and medium seam heights. 

Electrical reliability of longwall systems was reported to be good. No 
consistent failure trends were reported from mine to mine except for some 
incidence of failures related to cable damage. 

System Servicing and Fault Isolation 

Several features can be implemented during system installation to facili- 
tate servicing of the illumination system and to prevent interference with 
machine servicing. Power-supply boxes should be located at protected, but 
accessible, locations. (Tram cab installation, however, is usually unde- 
sirable because of the discomfort it causes for machine operators.) Location 
of luminaires on machine covers over frequently accessed machine components 
(e.g., hydraulic reservoirs) should be avoided if possible. Also, additional 
cable slack should be provided to permit the machine covers to be set aside 
without removing the luminaire. Ouick-release mounting brackets are useful in 
situations where luminaire removal is necessary (e.g., the fixture must span 
across two cover pans) . Figure 6 shows a simple design which is not easily 



252 




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253 

damaged by bending. Some mines refabricate machine covers to accommodate the 
luminaires . Hinge brackets should be used on recessed luminaires to facili- 
tate lamp changes. 

Numerous hardware-design features also affect ease of servicing. Slip- 
fit glands may facilitate gland removal on some X/P enclosures, where, if 
threaded glands are used, adjacent glands must be removed to gain access to 
the one to be removed. Lamp-changing procedures vary significantly between 
different fixture designs. If lamp-changing is to be performed at the face, 
use of fixtures posing difficulty should be avoided. Slip-fit packing glands 
and connectors greatly facilitate luminaire change-out. Ballast packaging 
arrangements also vary significantly between different manufacturers' designs, 
and they should be examined to assess the difficulty of changing out the 
ballasts or accessing them when making electrical tests. One mine has 
modified their controller boxes to house the ballasts on a swing-out panel. 

The difficulty of isolating electrical faults is highly dependent on 
system design. As expected, few mines reported troubleshooting problems with 
incandescent systems, not only because mine personnel are familiar with the 
systems, but also because of their inherent circuit simplicity. Somewhat 
surprisingly, more mines reported troubleshooting difficulty with core-and- 
coil ballasted systems than with the more complex electronic systems 
(primarily, intrinsically-safe systems). From the comments of mine personnel, 
it appears that design of the electronic systems facilitates isolation of 
routine failures (once maintenance personnel gain some familiarity). None- 
theless, it should be noted that a small number of mines discontinued use of 
the electronic systems because of frequent electrical failures and extreme 
troubleshooting problems. When mine-power parameters are poor, resulting in 
frequent and varied failures, the complexity of the electronic systems may be 
a disadvantage . 

The most frequently cited troubleshooting problem on conventionally- 
ballasted systems results from use of dual-lamp ballasts which drive the lamps 
in series. A number of common failures (burnt-out lamp(s), bad ballasts, 
etc.) result in the same obvious manifestation — the lamps on the circuit do 
not light . Resolution of the ambiguity requires performance of a series of 
tests which may involve considerable time. 

Both electrical troubleshooting and component replacement are greatly 
facilitated on systems employing plug-type connections between individual 
circuit components or groups of components. Specific advantages of this 
design aspect include : 

(l) During electrical troubleshooting, circuit redundancy is an easily- 
used advantage. Leads can be easily switched to an existing dupli- 
cate unit to test a suspect one. Similarly, a suspected faulty unit 
is physically easy to replace with a new unit. 



254 

(2) When components are grouped (e.g., luminaire/integral ballast/ 
connector), fault isolation within the group need not be done at the 
face. Rather, the entire group can easily be changed-out , mini- 
mizing machine downtime. 

(3) When line-installed connectors are used, cable continuity checks are 
facilitated. (This is particularly important on longwalls, where 
cable failures are frequent and check procedures tedious.) 

Integrally ballasted, connector-equipped, X/P fluorescent luminaires 
which were originally designed for longwall application are now seeing some 
application on mobile face machines. Advantages over standard fluorescent 
fixtures include (l) the single ballast-to-lamp-ratio facilitates trouble- 
shooting, (2) distinction between failed ballasts and lamps at the face is 
unnecessary, (3) luminaires are readily changed out, and (4) need for a 
separate X/P enclosure to house the ballasts is eliminated. When applying 
these systems, care should be taken in establishing pigtail lengths. Stand- 
ardization on a single pigtail length may not be desirable if protected cable 
runs are to be maintained. 

PERSONNEL ACCEPTANCE 

During the study, 384 machine operators were interviewed concerning their 
evaluation of the illumination systems on their machines. A consistent line 
of questioning was employed; and they were asked about their overall appraisal 
of the system, existence of several specific problems, and suggestions for 
improvements . 

Overall Acceptance 

On room and pillar applications, 74 percent of the machine operators 
viewed favorably the systems on their machines or the machines they interface 
with. A majority of machine operators' expressed a favorable overall opinion 
regardless of the particular type of machine or the seam height of the appli- 
cation. On longwalls, general acceptance was even higher, with 96 percent of 
the face-crew members expressing an overall favorable opinion. 

Acceptance of the systems on room-and-pillar machines was shown to 
increase with length of the operator's experience with the system, as shown in 
Table 3. This implies that a period of adjustment was necessary for many of 
the machine operators before they began to like the systems; this implication 
was further supported by numerous comments made to this effect by the machine 
operators . 

No significant difference in the overall appraisals of the machine oper- 
ators was found when comparing acceptance of fluorescent, H.I.D., and incan- 
descent systems. Excluding shuttle-car operators, machine operators expressed 
favorable opinions of 66 percent for fluorescent, 66 percent for H.I.D., and 
63 percent for incandescent systems. 



255 



TABLE 3. - Percent acceptance versus lighting experience 



Years experience with 
mine lighting system 



Percent favorable 
overall appraisal 



0.0 - 1.0 
1.0 - 2.0, 
2.0 - 3.0, 
>3.0, 



61 
65 
70 
82 



Acceptance decreased somewhat in lower seam-height applications, as shown 
in Table 4. However, the difference in acceptance was less than expected, 
particularly between applications in seams higher or lower than 42 inches. It 
was significantly less than that found in the Joint Committee (UMWA/BCOA/MSHA) 
Survey of 1978. Possible reasons for the difference between the surveys 
include modifications in system design as a result of the changes in enforce- 
ment policy which followed the 1978 survey and the fact that the machine 
operators have had several additional years to become adjusted to the systems. 
Regardless of the reason, the improvement in low-coal operator acceptance is 
welcomed . 

TABLE 4. - Percent acceptance versus seam height 



Seam height , 
meters (inches) 



Percent favorable 
overall appraisal 



>2 


.44 






(96) 


86 


1 


.07- 


2 


.44 


(42-96) 


74 


<1 


.07 






(42) 


69 



Specific Problem Areas 

A favorable appraisal of face-illumination systems does not preclude 
existence of significant problems. Luminaires covered with rags, paint, etc., 
are evidence of this. On room-and-pillar machine applications, numerous indi- 
viduals, including many of those who expressed a favorable opinion of the 
system on their machine, complained that the system (l) caused them discomfort 
or impeded performance of certain visual or manual tasks when working around 
the machine, or (2) did not optimally address their lighting needs for task- 
performance or safety. 

Glare-related complaints were most frequent. Excluding shuttle-car 
operators, 57 percent of the equipment operators cited a glare problem with at 
least one luminaire on their machine. The majority of complaints cited lumi- 
naires in close proximity to the individuals' normal work station(s). The 
frequency of these complaints was independent of the type of light source 
(fluorescent, H.I.D., incandescent). However, of the smaller number of com- 
plaints involving luminaires remote from the normal work stations, point- 
source lamps (incandescent and H.I.D.) were cited with much greater frequency. 



256 

Overall, the difference in the frequency of glare problems in the different 
seam-height ranges was not major, although there were differences for certain 
machines . 

On continuous miners, glare complaints most frequently involved the 
luminaire(s) on or immediately inby the operator's cab. A smaller, but sig- 
nificant, number of complaints involved the machine headlights. On retreat 
sections, men frequently work inby the machine when setting posts, and head- 
lights, if left operating, can be particularly glaring. 

The most common glare complaints on roof bolters involved (l) luminaires 
near the drill head, which bothered operators and helpers when drilling or 
performing helpers' duties, and (2) luminaires on or near the machine deck, 
which bothered operators when preparing bolts and changing bits and obscured 
vision of materials on the machine. Complaints were much more frequent on 
dual-head than single-head machines, but most luminaires cited in the com- 
plaints on dual-head machines bothered the operators only when intermittent 
tasks were performed. Many problems with luminaires mounted in the vicinity 
of the drill station on single-head bolters appeared particularly severe. 

The incidence of shuttle-car operators reporting glare problems with 
miner- or loader-mounted fixtures was insignificant in high seams but much 
more frequent in low (<42 inches) applications. On cutters, loaders, and face 
drills, most glare problems occurred when operating from the cab, from fix- 
tures in the immediate cab vicinity. 

Illuminated machine vicinities are typically the only lighted areas at 
the working face. When approaching or leaving these vicinities, workers' eyes 
must adjust to different brightness levels. The change can be abrupt (e.g., 
when passing through a check curtain) or more gradual. Overall, the pro- 
portion of individuals who indicated this posed problems for them was low. 
However, the incidence of the adaptation problem was significantly more fre- 
quent on (1) low-coal machines, and (2) dual-head bolters. Dual-head bolters, 
because of large machine dimensions relative to the mine entry, often require 
a larger number of luminaires to meet photometric compliance; and it is likely 
that the generally higher brightness levels increase this problem on these 
machines . 

Visible airborne dust and water spray often create a foglike condition 
around continuous miners. Light, primarily from machine-mounted headlights, 
reflects off the dust and spray cloud creating a glaring condition called 
"whiteout" which inhibits visual observation of the working face and other 
surfaces. When the dust cloud spreads to the outby portion of the machine 
(generally, only under unusual circumstances), light from the area luminaires 
contributes to the condition; in this case, vision is particularly impaired. 
Forty-three percent of the miner operators stated that the whiteout condition 
significantly inhibited their vision. 



257 

With increased light levels after implementation of machine-mounted 
lighting systems, contrast between the cap-lamp beam and surrounding surfaces 
is diminished, presumably reducing the effectiveness of the cap lamp as a 
means of signaling coworkers. Only 12 percent of the machine operators 
thought this was a significant problem. The following circumstances appear to 
affect the seriousness of the problem: 

(1) Direct Eye Contact - Operators indicated that when they can see the 
beam directly, there is no problem, but difficulty is increased when 
they must rely on reflected light. Accordingly, on some machines, 
the frequency of signaling problems was much higher in low seam 
heights where direct eye contact is difficult, and frequency was 
also higher among shuttle-car operators with offside cabs. 

(2) Anticipation - Operators commented that the problem is more signifi- 
cant with unexpected than anticipated signaling. 

Other problems cited with generally low frequency include (l) obstruction 
of visual avenues by the presence of a lighting fixture, (2) "hindrance- 
related" complaints where lighting fixtures are frequently bumped, physically 
interfere with performance of some tasks, or inhibit cab ingress or egress, 
and (3) heat complaints. A common practice in low coal, which should be 
avoided because of the serious discomfort it causes machine operators (because 
of heat and crowding), is location of luminaires or power supply enclosures on 
cab decks. 

Finally, machine operators have noted several cases where improved light- 
ing is desirable to meet their needs for task performance and monitoring of 
conditions. The most common recommendations are shown in Table 5. 

Approaches to Minimize Acceptance Problems 

Shielding and diffusing techniques are employed most frequently to con- 
trol glare problems. Shields must take into account the operator's various 
lines of sight to the fixture which, in turn, depend both on the particular 
work task in question and the work habits of the operator. Operators have 
suggested that adjustable shields be used to accommodate these variations. 

Changes in fixture location have frequently been made with great success. 
In particular, great care should be taken in location of fixtures on 
canopy or TRS structures on roof bolters. Often great improvement can be 
realized with minor relocations. Canopy-mounted fixtures on continuous miners 
are difficult to locate without being a glare problem, but several mines 
reported that glare problems are diminished if the fixtures are located as far 
toward the outby end of the cab as possible. Modification of canopy structure 
to recess the luminaire can diminish the problem for the operator, but compa- 
nies are often reluctant to do this lest the approval status of the canopy 



258 



TABLE 5. - Areas where machine operators recommended more/better illumination 



Machine 


Area 


Comment s 


Continuous miner 


Face 

Inby roof 
Tail area 


- Greater light intensity on the face is desir- 
able and "better" lighting is needed to pene- 
trate dust and spray. Primary concern is 
definition of coal marker beds and position of 
cutter bits to facilitate cutting operation. 

- Should be illuminated at higher level to 
monitor roof conditions. 

- Higher illumination level is desirable to 
reduce abrupt change in light levels when 
looking toward shuttle cars while loading. 

- A separately switched headlight directed at 
offside rib and floor would be desirable for 
backing up machine. 

- Improved visibility of tail boom desired to 
facilitate aligning of shuttle car with 
machine . 


Shuttle cars 


Inby/outby 


- Dual headlights generally preferred over 
single headlights because offside light 
improves positioning of vehicle relative to 
entries . 

- Headlights often mounted in poor locations 
, where they quickly become covered with 
mud/ coal . 

- On some vehicles (especially diesel scoops), 
headlights are obscured by machine bucket. 


Bolters 


Roof 


- Better lighting desirable to minimize shadows 
in cases where the coal/ roof parting leaves a 
rough surface. Shadows inhibit spotting of 
roof aberrations. 

- High light level on drill area is desirable 
but should be without glare. 


Loaders, cut- 
ters, face 
drill 


Face 


- High light levels on face/ inby area 
desirable . 

- Systems without adjustable headlights are 
undesirable on face drills because of dim 
spots which hinder drilling operation. 



259 

structure be changed. Some lighting manufacturers have obtained STE- 
extensions which permit substitution of the new, short, fluorescent luminaires 
in the canopy area; and this may offer glare advantage. 

On machines where top-deck visibility is essential (primarily roof 
bolters) , some companies reported that visibility is improved if "open" 
mounting brackets are used (Figure 7). These mounts increase light trans- 
mission to the deck surface and apparently diminish contrast problems which 
obscure visibility of objects on the deck surface. 

Improvement of face lighting is given high priority by many mine oper- 
ators. Frequently, additional headlights have been installed on continuous 
miners. Although increase of light levels is relatively simple, doing so in 
view of the whiteout problem is most difficult . Many mines have experimented 
with various headlight configurations, but the results they reported during 
the study were extremely contradictory. Design optimization criteria (e.g., 
beam type, lamp orientation, etc.) with relation to typical dust conditions, 
might result in great improvements in the effectiveness of continuous-miner 
lighting systems. 

Conclusion 

Although this paper has concentrated on problem areas, the successes 
shown by the study should not be overlooked : 

(1) Longwall lighting has been implemented with few problems at most 
mines, and both mine operators and face personnel are reporting many 
tangible benefits. 

(2) No particular maintenance problem is consistently severe on room- 
and-pillar applications, and many mines reported relatively low 
maintenance requirements (in mining terms) for this application. 

(3) Despite existence of several significant acceptance-related problem 
areas on room-and-pillar face machines, the majority of face equip- 
ment operators appraised their lighting systems favorably overall. 

Many of the existing problems can be minimized through more careful 
specification, design, and implementation of hardware and systems. In some 
cases, additional research is warranted. The successes to date should serve 
as a spur to continued evolvement of mine lighting so that the full benefits 
in personnel safety, comfort, and productivity are realized. 



260 




FIGURE 7. - "Open" construction of angle-mount bracket increases 
light transmission to machine deck surfaces. 



261 



TITLE OF PAPER: Efforts to Design Lighting 
Systems into Underground 
Mining Equipment 

AUTHOR: Mr. Owen J. Wright 
Lee-Norse Company 
Pittsburgh, Pennsylvania 



Mr. Wright has been with Lee-Norse Company for the last 10 years, and 
is currently an Engineering Specialist-MSHA. He attended West Virginia 
University, where he was an electrical engineering major for four years. 
His professional experience includes service with Glenn L. Martin Company 
for four years, where he held the positions of draftsman, loftsman, and test 
engineer. He served 1 year, 7 months in the U.S. Navy as a radio technician; 
and worked three years as a structural layout and details draftsman for 
Archineer Design Associates, Fairmont, West Virginia. He was also affiliated 
with Fairmont Machinery Co. (Consolidation Coal Company) eight years, as 
structural, piping, and electrical layout and details checker; shop liaison; 
and shuttle-car project engineer. He was with Lee Engineering Division of 
Consolidation Coal Co. four years, as engineer; four years with Thomas Tanks, 
Inc., Columbus Ohio, preparing estimates, bids, design, and detail of field- 
erected storage tanks, and supervised fabrication and erection; and with 
Transmission Products (Division of Galis Machine Co.), Columbus, Ohio, as 
Engineer, and obtained approvals of underground mining machines, three years. 



262 

EFFORTS TO DESIGN LIGHTING SYSTEMS INTO UNDERGROUND MINING EQUIPMENT 

by 
Owen J. Wright 1 

ABSTRACT 

The Coal Mine Safety and Health Act of 1969 directed the Secretary of the 
Interior to propose standards, by December 31, 1970, for permissible illumina- 
tion of all working places in a coal mine, while persons are working in the 
area. Such standards were formulated and printed in the Federal Register on 
December 31, 1970. As a result of written comments, and subsequent consulta- 
tion meetings, presenting suggestions and objections; these proposed standards 
were withdrawn. 

After consideration of the many comments, suggestions and objections, a 
revised standard was proposed and published in the Federal Register on October 
27, 1971. Again, written comments were invited and received. After extensive 
investigation, experimentation and testing; a public hearing was held on April 
4, 1974. 

Following this hearing, on June 28, 1974, a finding of fact was publish- 
ed. It was found that technology existed and stationary and machine mounted 
systems had been developed, which would produce the required 0.06 foot- 
lamberts of illumination. However, the difficulty in adapting the systems to 
the many types of face machines and equipment; and the lack, in the mining 
industry, of expertise in the illumination engineering field; plus the lack of 
simple instrumentation, usable underground, still presented a problem in the 
enforcement of the regulations. 

A publication in the Federal Register, on April 1, 1976, served notice 
the instrumentation and technology was then in existence; and that the reg- 
ulations would be promulgated on October 1, 1976. 

After seven years of investigation, resarch, testing and evaluation, the 
illumination standards were promulgated, as scheduled, on October 1, 1976. 
The promulgation allowed a period of eighteen months to bring the working 
areas of all mines into compliance with 30CFR, Part 75.1719. 



Engineering Specialist, MSHA, Lee-Norse Company, Pittsburgh, PA. 



263 

TEXT 

Illuminate all working areas of all underground coal mines in the United 
States. Thousands of unlighted machines were working in hundreds of unlighted 
areas. Few people, if any, fully realized the magnitude of this gigantic 
task. 

From the inception of the mine illumination program, the need for inte- 
gration of lighting into machine designs was, of necessity, completely over- 
shadowed by the need to retrofit the many and varied models of machines, then 
in the working places. As a result, nearly all illumination systems developed 
were "add-on" features of existing machine designs. 

Mining Enforcement and Safety Administration (MESA), later becoming Mine 
Safety and Health Administration (MSHA) , worked, almost entirely, with manu- 
facturers of luminaires and related lighting equipment in the development of 
lighting systems. Although there was some consultation with mine equipment 
manufacturers, by these lighting companies, there was little direct involve- 
ment of the machine designers and builders. 

A few equipment manufacturers and mine operators built dark rooms, sim- 
ulating mine environment, for use in the design and evaluation of illumination 
systems. However, most systems are still being developed as "add-ons". It is 
not practical to redesign a machine, or a series of machine models, just to 
satisfy lighting requirements. Some manufacturers elect to ignore lighting, 
and let illumination fixture manufacturers supply the systems for their ma- 
chines . 

The process of incorporating an illumination system into a machine design 
is not a simple one. A preliminary layout must be made to determine luminaire 
locations to produce an adequate light output pattern. A prototype chassis, 
or a mock-up, must then be made, with recesses for protective mounting of 
light fixtures. The lights must be protected by locations, or shielding must 
be provided, as a requirement for approval under Part 18 of Title 30, Code of 
Federal Regulations (30CFR). 

Once the overall lighting system layout has thus been tentatively deter- 
mined, an investigation must be made to determine any interference with the 
location of other electrical, mechanical or hydraulic components of the ma- 
chine. Functional or space requirements may limit or preclude the relocation 
of these other components. In these instances, when interference occurs, it 
is necessary to relocate the luminaire. Relocation of a light may effect the 
machine light output pattern to the extent that installation of additional 
lights may be required, to maintain compliance with the regulations. 

In some instances, the relocation of luminaires is not practical. This 
may require the redesign of the interfering component, to make mounting 
space available for the luminaire. Deviation from the use of standardized 



264 

components may result; and if the component is an electrical explosion-proof 
enclosure, will require an extension of certification or a new certification. 

It becomes evident that, although there are obstacles to the integration 
of lighting in an original machine design, they are not insurmountable. 
However, inclusion in an existing machine design may cause a prohibitive 
amount of redesign and additional cost. Thus, the "add-on" type of lighting 
is still predominantly used. 

A mine operator often desires to purchase an unlighted machine and apply 
an illumination system of his own design, or a design purchased from a lumi- 
naire manufacturer. For this reason, the lighting system must be offered as 
an option on the overall machine design and approval. This, again, encourages 
the use of "add-on" systems. In other cases, the operator desires a system 
designed by the machine manufacturer; but specifies a definite make of lumi- 
naire . As a result, alternates to the optional system must be offered. Thus 
MSHA acceptance of each alternate must be obtained, and separate statements of 
test and evaluation must be provided. 

Once a system is designed to produce a satisfactory light output and 
distribution, the problem of achieving an acceptable glare level rears its 
ugly head. Acceptable glare is very difficult to define. Comfort and ac- 
ceptability varies from one individual to another and must be acceptable to 
the machine operator, his helper and the operators of other machines working 
in the same area. Glare may be substantially reduced, by placing shields 
between the light source and the eyes of the observer. However, care must be 
taken to assure that the shields do not adversely effect the light distri- 
bution, to the extent that the system is no longer in compliance with the 
regulations. In the opinion of the writer, the final resolution of the glare 
problem must ultimately be the responsibility of the users of the machine, and 
must be solved while operating in the work area. 

Incorporating lighting in the overall machine has a distinct advantage of 
locating the luminaires so protection is provided against damage due to fall- 
ing material or rubbing against the mine roof or ribs. "Add-on" fixtures, of 
necessity, project above or from the sides of the machine, and are vulnerable 
to damage from these sources. Although it may not be immediately evident, the 
added protection of an integral lighting system may result in a significant 
decrease in machine maintenance and repair costs. This is especially true for 
machines working in low seam heights. 

In the case of an "add-on" system, the machine approval seldom includes 
the lighting electrical circuitry. This necessitates an application, by the 
machine user or manufacturer, for an extension of approval or a SNAP accep- 
tance, to electrically connect the lights to the machine power. The integral 
systems are covered by the approval and thus the additional paper work, and 
delay, is eliminated. 



265 

A "Statement of Test and Evaluation" (STE) is an important tool for the 
mine operator. Possession of an STE is assurance that a lighting system has 
been tested and is in compliance with the regulations. Thus, it is not nec- 
essary for a mine inspector to make measurements to determine compliance for a 
machine bearing an STE. There is, therefore, no loss of production time while 
the machine is repositioned and light readings taken. The STE is more readily 
processed for machines with integral lighting systems, since the installation 
drawings and wiring diagrams will exist as part of the machine approval pack- 
age. Thus, the number of additional drawings required for submittal is 
reduced . 

If there are disadvantages of the integral lighting systems when compared 
to "add-on" systems, they are not apparent at this time. Due to additional 
design and testing, more time and expense is required to produce a prototype 
machine. However, once this hurdle is cleared, there should be no further 
effect in the building of production machines of the same model. An increased 
selling price, due to the inclusion of lighting components, installation and 
testing costs; should compare favorably with the price of an unlighted machine 
with the cost of an "add-on" system included. 

A survey of the major mining machinery manufacturers revealed only one 
machine on the market with the designed-in illumination systems. Some manu- 
facturers may have systems in the design stage, but have nothing for release 
at this time. 

The Lee-Norse Company has built two prototypes of their Model LN800 
Continuous Miner, which has an integral illumination system, and now has this 
model in production. As a result of using the integral lighting, the LN800 
presents a smooth, flat top of the machine broken into easy "lift-off" covers, 
to facilitate machine maintenance. 

In general, integral lighting design of mining machines is just begin- 
ning. Since it may take years to develop new machine designs, there is little 
hope of swift emergence of the integrated systems. Also, equipment manufac- 
turers are being very cautious in incorporating existing light fixtures into 
new designs. Redesign of available lighting components, and the rescinding of 
certifications or acceptances by MSHA, could have a disastrous effect on newly 
marketed machine designs. These problems have arisen on several occasions, 
during the development of the "add-on" systems. Before incorporation into 
closely knit designs, the builders must be reasonably sure that component 
designs and acceptances are permanent. This is the result of an expensive 
lesson, learned by everyone concerned, in the development of the presently 
available lighting systems. 



266 



FLUORESCENT LIGHT FLUORESCENT LIGHT 




HEADLIGHT FLUORESCENT LIGHT 



FLUORESCENT LIGHT 




RIGHT SIDE OF MACHINE 



Figure 1. 



267 



FLUORESCENT LIGHT 



FLUORESCENT LIGHT 




FLUORESCENT LIGHT 



FLUORESCENT LIGHT 




a 



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Figure 2. 



268 



SIDE VIEW 



FRONT VIEW 





TYPICAL HEADLIGHT MOUNTING 



CANOPY 



FLUORESCENT 
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ID 



.25 



f 



CANOPY LIGHT MOUNTING 



Fluor, luminaire 




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note: view typical for 
luminaire on tram 
CONTROLLER also. 



LEFT SIDE 
COVER MOUNTING 




LEFT SIDE 
CONTROLLER MOUNTING 



Figure 3. 



269 



FLUORESCENT LIGHT 
HEADLIGHT 

.FLUORESCENT LIGHT 




LN800 TYPICAL LIGHT MOUNTING 




REMOVEABLE PANELS FOR 
MORE EFFICIENT MAINTENANCE 

Figure 4. 



270 



TITLE OF PAPER: Illuminating Large Surface 
Machines, Problems and 
Solutions 

AUTHOR: Mr. David Hottinger 

Phoenix Products Co., Inc. 
Milwaukee, Wisconsin 



Mr. Hottinger is a Project Engineer at Phoenix Products Co., and has 
been associated with the company since 1977. He is a graduate of the 
University of Wisconsin, and holds a B.S. degree in electrical engineering. 

His lighting experience includes design of fixtures for both underground 
and surface coal-mining operations, and includes excellent practical experi- 
ence in illuminating areas on and around surface mining equipment. 



CO-AUTHORS: Mr. Kenneth Faux 

Manager of Engineering 
Phoenix Products Co., Inc. 
Milwaukee, Wisconsin 



Mr. R. 0. Yantz, Manager 
New Products Development 
Phoenix Products Co., Inc. 
Milwaukee, Wisconsin 



271 

ILLUMINATING LARGE SURFACE MINING MACHINES, PROBLEMS AND SOLUTIONS 

by 
David D. Hottinger 1 , Ken R. Faux 2 , and Rupert 0. Yantz 3 

ABSTRACT 

This paper addresses the problems and solutions of providing and 
measuring illumination on and around surface mining machines. Primarily, a 
Bureau of Mines sponsored project is discussed in which the feasibility and 
effectiveness of providing dragline lighting to the MSHA proposed Federal 
Regulations for surface mining illumination was demonstrated. The demon- 
stration involved illumination system design, installation, and evaluation. 
Special emphasis is given to a unique computer aided illumination system 
design tool employed on this project. In addition, problems encountered in 
design, installation, and photometric evaluation are reviewed. 

INTRODUCTION 

Only a minimum amount of illumination is generally provided for many 
types of mobile surface mining equipment. This condition presents a hazard to 
operating personnel working on and around such equipment. To reduce this 
hazard MSHA has proposed safety regulations requiring minimum levels of illu- 
mination for hazardous zones on and in the immediate area surrounding surface 
mining equipment . This paper describes a three phase Bureau of Mines spon- 
sored project demonstrating the feasibility and effectiveness of providing 
dragline illumination in compliance with the proposed MSHA regulations as 
published in the January 13, 1977, "Federal Register" CFR 77.207 and summa- 
rized in Figure 1. 

During Phase I of the project three draglines with 9.2 m 3 (12 yd 3 ), 
15.3 m 3 (20 yd 3 ), and 26.8 m 3 (35 yd 3 ) buckets were identified and selected. 
An evaluation of existing illumination levels was first made and then a 
computer aided design of the proposed lighting systems was performed. Only 
currently available production lighting equipment was considered and lighting 
system components were selected on the basis of their ability to survive in 
the surface mining environment of shock, vibration, and dirt accumulation. 

project Engineer, Phoenix Products Company, Inc., Milwaukee, WI . 

^Manager of Engineering, Phoenix Products Company, Inc., Milwaukee, WI . 

3 Manager - New Product Development, Phoenix Products Company, Inc., 
Milwaukee, WI . 



272 



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Lamp selection was based on efficacy and suitability to each situation. 
Computer calculated lighting levels for each of the three lighting systems 
included a 33 percent lamp lumen depreciation factor in meeting the proposed 
regulations . 

In Phase II of the project each of the lighting systems was installed. 
After installation a photometric survey for each of the three lighting systems 
was performed and evaluated in accordance with the methods outlined in the 
proposed regulations. 

Phase III of the project included a second photometric survey for each of 
the three lighting systems after a three month period of lighting system 
operation. Lighting system hardware failures were logged and evaluated. 
Reactions of the workers to the lighting system were also recorded at this 
time . 

The project represented by this paper demonstrated the capability of 
providing illumination levels meeting or exceeding the proposed MSHA regu- 
lations for dragline mounted lighting systems using currently available 
technology and hardware . 

This paper presents only a summary with typical examples of the data and 
results obtained. Presented first is a discussion of the tasks accomplished 
in each phase of the project with results and special problems encountered 
highlighted. Observations made during the project and comments pertinent to 
those observations are presented next. Conclusions and recommendations 
resulting from the entire effort are discussed in the final portion of this 
paper . 

In the interest of condensing this paper and keeping it informative, data 
for only the Marion 184-M dragline are included as representative of all three 
draglines involved in the demonstration. However, unique features, problems, 
and solutions for the other two draglines are discussed. 

A complete report of the project conducted is available through the 
Bureau of Mines . 

DESCRIPTION OF DRAGLINES 

As the initial task of Phase I, the following three draglines were 
selected for the illumination demonstration project. 

A. Marion - Type 184-M Dragline 

Operated By: Cobb Coal Company 
Location: Saragossa Surface Mine 
Carbon Hill, Alabama 

The Marion Type 184-M dragline is a crawler type machine with a main 
frame measuring approximately 5.8 m (19 ft) wide by 10.1 m (33 ft) long by 



274 

6.1 m (20 ft) high. The machine is constructed with a 36.6 m (120 ft) long 
boom and a 9.2 m 3 (12 yd 3 ) bucket. Accessory electric power is supplied by an 
auxiliary diesel driven 37.5 KVA 60 Hertz generator. The generator had an 
excess capacity of approximately 8 KVA available for additional lighting at a 
nominal 440 volts. Photographs of this dragline are included in Figure 2. 
This, the smallest of the three draglines, was selected primarily as the most 
detrimental shock and vibration environment for lighting equipment. 

B. Page - Model 7-32 Dragline 

Operated By: Westmoreland Coal Company 
Location: Westmoreland's No. 8 Surface Mine 
Leivasy, West Virginia 

The Page Model 7-32 dragline is a walking type machine powered by diesel 
motors. The main frame measures approximately 9.5 m (31 ft) wide by 19.4 m 
(63.5 ft) long by 9.1 m (30 ft) high. The machine is constructed with a 61 m 
(200 ft) long boom and a 15.3 m 3 (20 yd 3 ) bucket. Power for the original 
lighting equipment was supplied by a 15KW D.C. generator driven by one of the 
main diesel motors. The light output from fixtures connected to this gener- 
ator was very unstable and diminished significantly as the diesel motor RPM 
dropped under heavy loading. A photograph of this dragline is shown in 
Figure 3. 

C. Marion - Type 7800 Dragline 

Operated By: Bankhead Mining Company 
Location: Parrish Surface Mine 
Route 2 
Parrish, Alabama 

The Marion Type 7800 dragline owned by Bankhead Mining Company is a 
walking type machine with a main- frame measuring approximately 16.2 m (53 ft) 
wide by 20.1 m (66 ft) long by 10.7 m (35 ft) high. The dragline is con- 
structed with a 79.3 m (260 ft) long boom and a 26.8 m 3 (35 yd 3 ) bucket. The 
machine was driven by electric motors with power supplied by a 7200 volt A.C. 
trailing cable. A step down transformer supplied 480 volt power for operation 
of the lighting system. Photographs of the machine are shown in Figure 4. 

INITIAL EOUIPMENT AND PHOTOMETRIC SURVEY 

As the second task of Phase I the existing lighting system installed on 
each machine was inspected to determine type, location, state of repair, 
design, and mounting. External photometric measurements were made in accord- 
ance with the proposed regulations summarized in Figure 1. Light level read- 
ings were taken around the main frame, beneath the main frame (in work or 
travel areas) , on the main frame and boom walkways and beneath the boom. 
Photometric layouts were then plotted for each of the three machines to 
determine areas of compliance, or severity of non-compliance. Some areas of 
the draglines were so poorly lighted that readings indicated light levels 
below 0.11 Lux (0.01 ft-c), the limit of sensitivity of the measuring 



275 




Dumping at max. spoil pile height 




Digging at edge of pit 
FIGURE 2. - Marion 184-M dragline photograph of digging operation. 



276 




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278 

instrumentation. This low light level was a result of either failure to 
relamp fixtures or to provide for illumination of specific areas including 
walkways and the area around the main frame. The initial photometric survey 
of the Marion Type 184-M dragline, Figure 5, was typical of the lighting 
condition existing around the three draglines during the initial investiga- 
tion. Lighting levels were well below the proposed MSHA requirements. Figure 
5 is also typical of the photometric layouts prepared for all other areas, in 
which illumination was measured, on all three machines. 

The Page Model 7-32 dragline had the unique feature of a 15KW D.C. gener- 
ator coupled to the main diesel . The result was that light output varied 
significantly with machine loading. This machine was retrofitted with a 25KW 
A.C. diesel powered motor generator set to eliminate lighting level variations 
and to allow the use of efficient conventional high intensity discharge light- 
ing equipment . 

The Marion Type 7800 dragline was the largest dragline included in the 
study and the only one with power supplied by a trailing cable. No illumi- 
nation was originally provided for tending the trailing cable during walking 
operations at night. Individual operators reported difficulty in "keeping 
track" of the trailing cable resulting in several incidents of severing the 
cable during night walking operations. 

As part of the initial photometric survey, available engineering drawings 
were reviewed and visual observations made of all three machines to locate 
areas requiring illumination and identify suitable mounting positions. Par- 
ticular attention was given to selecting potential mounting locations which 
were structurally sound, accessible for maintenance, and free of light 
blocking obstructions. 

LIGHTING SYSTEM DESIGN 

Until recently lighting equipment was applied to draglines primarily for 
productive purposes in an unsystematic manner. A minimum number of lighting 
fixtures were used only at key areas for safety or individual task perfor- 
mance. The potential benefit of improved personnel safety and productive 
capability to be realized by an integrated systematic application of lighting 
equipment to the individual dragline and the total operational function was 
not fully appreciated or evaluated. The objective of this project was to 
illuminate three draglines in accordance with the proposed MSHA requirements 
in order for the Bureau of Mines to evaluate improved personnel safety. A key 
element used in the lighting system design phase was a computer program desig- 
nated "CALL" for Computer Aided Lighting Layout. "CALL" was developed by 
Phoenix Products Company, Inc., specifically to assist the lighting engineer 
in designing lighting systems for unique applications such as draglines. 



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FIGURE 5. - Marion 184-M photometric layout of existing lighting, 



280 



"CALL" Program 

Calculating illuminance is not an especially difficult problem, but it is 
extremely tedious and time consuming if done by hand. This is due to the fact 
that illuminance values must be calculated for a series of individual points 
and each point value is a total accumulation of the outputs of each and every 
contributing light source. Factors involved in each single source individual 
point calculation include: distance between source and point, beam angle 
(angle formed by source aim point, source, and calculated point), and the 
angle formed by a vertical axis through the point and the light ray striking 
that point. In addition, it is necessary to refer to photometric data for 
each light source in the problem to find the light intensity projected on each 
calculated point . 

To get an idea of the magnitude of this problem assume we want to calcu- 
late the illumination around a 7.62 x 9.14 meter (25 x 30 foot) dragline or 
shovel main frame. The proposed regulations specify a 6.1 meter (20 foot) 
wide area on all four sides around the main frame with light readings to be 
taken on the corners and center of every 9.26 m (100 ft ) area. This trans- 
lates into about one hundred individual points, and each point will have an 
average of at least three sources contributing light to it. This then gives 
us, for just around the main frame, a lighting problem of more than three 
hundred repetitious and lengthy trigonometric problems with three hundred 
referrals to and interpretations of photometric plots or tables. The point of 
all this is that lighting problems are ideally suited for computerization and 
impractical, at best, to do otherwise. To take advantage of the powers of the 
computer, Phoenix Products Company developed the "CALL" program in 1974 as an 
illumination system design tool. In as much as our lighting products are 
designed for specialized industrial applications, "CALL" was developed to 
handle a variety of lighting problems as diverse as liquid natural gas tank 
ships, nuclear power plants, and- offshore drilling platforms. Most of these 
have nothing in common with the more conventional problems associated with 
office, roadway, or high bay industrial lighting. The more conventional 
lighting problems involve a single type source, a uniform mounting height, and 
a level horizontal surface upon which the light falls. The mining industry 
demands unconventional lighting. For example, in a single lighting problem 
more than one type of lighting fixture must generally be used, the desired 
fixture mounting heights can range from near the ground to the tip of a boom 
or mast and the work plane can be anywhere from horizontal to vertical and 
run anywhere from 60.96 meters (200 feet) below the normal ground surface to 
60.96 meters (200 feet) above. 

In the "CALL" program, photometric data for fixture and lamp combinations 
are stored in computer memory under a discrete serial number. Each lighting 
problem is defined by an X-Y coordinate system and each light source is 
identified by its serial number and entered into the computer along with its 
X and Y location, height, elevation aiming angle, and azimuth aiming angle. 
In addition, identification of the project and a description of the run is 
entered. The computer printout provides a scaled plot of the calculated 



281 



illuminance on a rectangular coordinate system with the Y-axis across the 
printout sheet and the X-axis down the length of the printout. An asterisk 
(with total accumulated lux or footcandles) is printed at the intersection of 
each ordinate and abscissa selected for a calculation by the print option. 
Scale for each printout is selected to some convenient scale from 2.54 cm 
(1 inch) equal to 30.48 cm (1 foot) up to 2.54 cm (1 inch) equals any whole 
number. Illumination points can be printed on several optional spacings. The 
most dense is on corners and centers of 2.54 cm (1 inch) squares. Such a 
printout option, with a scale selection of 2.54 cm ( 1 inch) equal to 3.048 m 
(10 feet), would provide "to scale" illumination point printouts on 3.048 m 
(10 foot) squares at corners and center over the entire area under study. 
This option is identical to the grid pattern required for photometric 
measuring in the proposed Federal Regulations. "CALL" can handle, in a single 
lighting problem, one to ninety-nine fixtures each mounted at different 
heights, X-Y locations, elevation aiming angles, and azimuth aiming angles. 
In addition, twenty different types of fixtures with dissimilar photometric 
characteristics can be included in a single problem. It is this flexibility 
that allowed "CALL" to handle the unconventional lighting problems demanded by 
this project . 

The "CALL" program uses candlepower distribution curves, such as those 
shown in Figure 6, for each fixture and sums the light contributed by each 
fixture at every point in a predetermined grid pattern. The data entered in 
the computer are as follows : 

LP# - Serial number assigned to each fixture. 

Type - Computer code number of candlepower curve for each fixture. 

Loc X - The X coordinate location of the fixture. 

Loc Y - The Y coordinate location of the fixture. 

Height - The fixture mounting distance above a predetermined X-Y 

coordinate grid plane. 

Elev - Elevation is the fixture aiming elevation angle above the 

perpendicular with zero being taken as the fixture pointing straight 

down . 

Azimuth - Azimuth is the fixture aiming angle of rotation in a counter 

clockwise direction relative to the X-Y plane. Zero azimuth angle 

indicates the center of the fixture beam pattern is aimed in the 

positive X-direction. 

Once the location and aiming information for each fixture in a lighting 
system has been entered in the program, the engineer enters the desired grid 
plane information. The computer calculates the contribution of light at each 
grid point from every fixture in the lighting system and prints the corre- 
sponding lux or footcandle value at each grid point . Figure 8 is an example 
of the type of scaled computer printout "CALL" generates. 

While the computer is very accurate in making the individual calcula- 
tions, the result is only an estimate. The accuracy of the estimate depends 
on several factors including: 



282 



MODEL SRS-EB-400 FIXTURE 
WITH 250 WATT HIGH 
PRESSURE SODIUM LAMP 



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WITH 400 WATT HIGH 
PRESSURE SODIUM LAMP 



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WITH 1000 WATT HIGH 
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FIGURE 6. - Fixture candlepower distribution curves 



283 

Lumen Output 

Initial lamp lumen output varies approximately ±20 percent between indi- 
vidual production lamps from the nominal rated values presented in the manu- 
facturers literature. All candlepower distribution curves are corrected to 
the nominal rated values presented in the manufacturers literature. 

Lamp lumen depreciation over life is significant. The 1000 watt HPS lamp 
has an initial rated lumen output of 140,000 and a 126,000 lumen output at 
50 percent rated life or 12,000 hours at 10 hours operation per start. This 
represents a 10 percent reduction in light output. If the lamp is started 
more frequently, the lumen output will depreciate faster. 

Lamp lumen output changes with variations in line voltage. A 120 volt 
incandescent lamp operated at 116 volts will experience a 10 percent decrease 
in light output . A 400 watt high pressure sodium lamp operating with a con- 
stant wattage autotrans former will experience a 10 percent decrease in light 
output with a 10 percent decrease in line voltage. 

Fixture lumen output will vary with the accumulation of dirt on the lens 
or reflector. Dirt depreciation factors are tied to the specific application 
and frequency of maintenance . 

Candlepower Curve Output 

Manufacturing variation in reflector shape and position can easily cause 
a 10 percent reduction in candlepower contributing to a point in a grid 
system. 

Lamp location variations can result in either a reduction in the candle- 
power contributing to a point in a grid system or a shift in the whole beam 
pattern. 

Secondary reflections of light off machine structures can result in 
errors. Reflections off the walls of a light colored machine house can be a 
source of such an error. 

Geometrical Relations 

Fixture beam pattern blockage by the mechanical components of the machine 
can result in drastic reductions in the candlepower contributing to a point in 
a grid system. The "CALL" program makes no allowance for light level losses 
due to beam pattern blockage by mechanical machine components. Machine 
obstructions that result in light level calculation errors include the boom 
steel matrix structure, support structures for the feet on walking draglines, 
rails for maintenance cranes extending from the rear of the machine house, and 
various walkways. During installation care must be taken to avoid light 
blocking obstructions. 



284 

Perpendicularity of the ground plane to the vertical center line of the 
machine house will significantly effect fixture aiming and light level 
measurements . 

Equipment Selection and Application 

Floodlighting was used wherever possible for area lighting. By design, 
spill from these lights was used to provide lighting for the various walkways. 
This approach minimized the total number of individual fixtures required for 
each dragline lighting system. High Intensity Discharge — "H.I.D." — lamps, 
especially High Pressure Sodium, were used whenever practical because of the 
high efficacy and long life of this lamp. 

The incandescent lamp produces light by heating a tungsten filament. 
Since the filament is heated to very high temperatures it can easily be 
broken. Special lamps can be made more resistant to mechanical stress, but 
are still limited in lamp life to between 2,000 and 6,000 hours. The high 
pressure sodium lamp consists of a translucent ceramic arc tube with an elec- 
trode sealed in each end. Light is produced by a high temperature arc stream 
between the two electrodes. This structure is very strong and able to resist 
very high shock and vibration stresses. A lamp life of up to 24,000 hours 
makes this lamp very desirable for use on surface mining equipment . 

Illumination levels under the main frame of the machine were computed at 
ground level instead of 0.76 m (30 in.) above the ground. Because of the very 
restricted mounting height in areas beneath the main frame, lighting fixtures 
located in this area are very close to the surface being illuminated. Meas- 
uring light levels 0.76 m (30 in.) above the ground — half the distance between 
the fixture and the ground in one case — presents a distortion of the actual 
illumination contributing to the seeing conditions for the individual miner. 

The access walkways on the main frame of each dragline were illuminated 
by spill from the lighting fixtures used to illuminate the area around the 
main frame. Light for the ladders on the walls of the main frame and on the 
gantries came from the lighting fixtures used to illuminate the area around 
the main frame or the roof. Since the lighting fixtures are aimed nearly 
parallel with ladders or located behind them, the present light level measure- 
ment requirements could result in unrealistic readings even though a ladder is 
well lighted for functional use. 

Boom walkways were illuminated by floodlights mounted on the main frame 
and/or on the main frame gantry. This lighting system design approach was 
used to reduce the total number of the lighting fixtures mounted on the boom. 
However, walkways near the tip of each boom required boom mounted lighting 
fixtures to provide acceptable illumination levels. Since all the lighting 
fixtures mounted on the boom were mounted close to the walkway for ease of 
maintenance, light levels were calculated at the illuminated surface rather 
than 0.76 m (30 in.) above it. 



285 

During the initial equipment and photometric survey, each dragline oper- 
ator requested additional light be directed at the point sheave of the boom to 
improve the operator function of judging the closeness of the bucket and cable 
knot to the point sheave. A 250 watt high pressure sodium lighting fixture 
was mounted on the boom of each dragline and directed towards the hoist rope 
line near the point sheave. This lighting fixture was only a partial solution 
to the problem. The additional light did illuminate the bucket as intended. 
However, the boom structure prevented the operator from seeing the point 
sheave from his control station. The improved lighting did make it easier for 
the operator to estimate the closeness of the bucket knot to the point sheave. 

Lighting Level Calculations 

After investigating each dragline for the application of lighting 
fixtures, specific areas and equipment were identified and evaluated in the 
"CALL" program. The results of the study for each dragline were presented in 
summary drawings giving the location and a complete description of each light- 
ing fixture in the lighting system. An outline of each dragline or dragline 
section was superimposed on the appropriate computer profile to indicate the 
relative location and estimated light levels. Since the lighting problems of 
all three machines are similar, this paper presents only the data and results 
for the 184-M dragline as being typical. Only exceptions due to unique 
features of the other two draglines are discussed. 

Marion Type 184-M Dragline 

Figure 7 presents plan and elevation views of the location and aiming of 
each lighting fixture. Figures 8 through 12 present the "CALL" program light- 
ing profiles for the various areas included in the study. Lighting fixtures 
16 and 17 shown in Figure 7 were selected to evaluate incandescent lamp life 
in the shock and vibration environment presented by the boom. 

The boom walkway on this dragline runs along the top surface of the boom 

leaving no possibility for lighting the tip of the boom from gantry mounted 

floodlights. Any overhead fixture mounting structure would be subject to 

damage by the boom support cable. Fixtures 16 and 17 shown in Figure 7 were 
mounted just above the boom walkway hand rail. A potential solution to this 

problem, not evaluated in this study, would be to illuminate the grating that 
forms the walkway from below. 

Page - Model 7-32 Dragline 

The unique feature of this machine was that the tailpiece only cleared 
the ground by approximately 0.61 m (2.0 ft) as shown in the photograph Figure 
13. Providing illumination in this area was not considered photometrically or 
mechanically practical. 



286 



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287 



MARION 1B4-M DRAOLINE LIGHTING PROFILE ILLUMINATION LEVEL UNDER MAIN FRAME 
ILLUMINATION VALUES REPRESENT CUMULATIVE' RAW FOOTCANDLES NO MAINTENANCE FACTOR WAS USED 

LP # S/¥ _ X-LOC" Y-LOC HEIGHT FLEV AZIMTH LP-FACTOR IV R-VALUE LAMP DESCRIPTION 

1 107 ~ 40.00 SO. 00 8. BO 50.00 168.00 1.00 10.49 H175RDXFL39-22 MERCURY VAPOR 
Z_ 107 40.00 38.50 8.80 50. 00 192.00 1.00 10.49 SAME AS LAMP ABOVE 

3 107 49.00 20.00 8.80 45.00 12.00 1.00 8.80 SAME AS LAMP ABUVE 
4 107 .49.00 38.50 8.80 45.00 348.00 1.00 8.80 SAME AS LAMP ABOVE 

SCALE IN BOTH DIRECTIONS (1 INCH = 5.0 FT. ) 

1 XY — > 15.0 2-0.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65. 

' 17. 5 ' 22. 5 ' 27. 5 ' 32. 5 ' 37. 5 ' 42. 5 ' 47. 5 ' 52. 5 ' 57. 5 62. 5 
V ,,,,,,.. i • t i 

15. — ♦»#*•♦» 

0. 76 0. 89 0. 96 0. 98 O. 95 85 0. 71 



17. 5— 




FIGURE 8. - Marion 184-M dragline lighting profile under main frame. 



288 



MARION 184-M DRAGLINE LIGHTING PROFILE ILLUMINATION LEVEL ON ROOF OF MAIN FRAME 

ILLUMINATION VALUES REPRESENT CUMULATIVE RAW FOOTCANDLES NO MAINTENANCE FACTOR WAS USED 

LIGHTING FIXTURES SRS175MB ( 10016) 



LP # S/N X-LOC Y-LOC HEIGHT ELEV AZIMTH LP-FACTOR IV R-VALUE LAMP DESCRIPTION 

1 107 32. 00 34.50 16.00 15.00 180.00 1.00 4.29 H175RDXFL39-22 MERCURY VAPOR 

2 107 32.00 24.50 16.00 15.00 180.00 1.00 4.29 SAME AS LAMP ABOVE 

3 107 32.00 34.50 16.00 25.00 0.00 1.00 7.46 SAME AS LAMP ABOVE 

4 107 32.00 24.50 16.00 25.00 0.00 1.00 7.46 SAME AS LAMP ABOVE 

( SCALE IN BOTH DIRECTIONS (1 INCH - 5.0 Fl.) 

. - 1 - I 

XY— > 20i 25. 30. 35. 40. 45. 50. 55. 60. 65. 70 



' 22. 5 ' 27. 5 ' 32. 5 ' 37. 5 ' 42. 5 ' 47. 5 ' 52. 5 ' 57. 5 ' 62. 5 



67. 5 



20. — » 



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5. 05 


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7. 76 8. 99 8. 85 7. 39 




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11. 54 13. 51 13. 28 10. 95 




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FIGURE 9. - Marion 184-M dragline lighting profile roof level of main frame, 



289 



MARION 184 -M DRACLINE L 10HTIN0 PROFILE ILLUMINATION LEVEL ALONG BOOM WALKWAY 

ULUMINATION VALUES REPRESENT CUMULATIVE RAW FOOTCANDLES NO MAINTENANCE FACTOR WAS USED 

INCANDESCENT FIXTURES ARE SRS-115-15C 



LP. » . S/N _ X -LQC 



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3 


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16 


3. 


90, 00 


42. 00 


17 


3 


105. 00 


38. 00 



HEIGHT ELEV AZIMTH LP-FACTOR IV R-VALUE 



8. 00 10. 00 230. 00 

8. 00 16. 00 130. 00 

34. 00 62. 00 O. 00 

3. 00 76. 00 350. 00 

3. 00 76. 00 10. 00 



1. 00 





1. 41 


1.00 





2. 2? 


1. 00 





63. 94 


1. 00 





12.03 


1. 00 





12. 03 



LAMP DESCRIPTION 

SRS-EA--400, COATED HPS LAMP 
SAME AS LAMP ABOVE 

SRS-EA-1000 CLEAR HPS 

150 PAR/3FL-120 INC 
SAME AS LAMP ABOVE 



SCALE IN BOTH DIRECTIONS (1 INCH =10.0 FT. ) 



XY — > 35 ; _45. 55.0 650 75.0 85.0 95.0 105.0 115.0 125.0 i: 

~~~ _' 40.0 ~' 50.0 '60.0 ' 70.0 '80.0 ' 90.0 ' 100.0 ' 110.0 ' 12Q. ' 130.0 



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FIGURE 10. - Marion 184-M dragline lighting 
profile boom walkway. 



290 



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291 



n8 »-H P R A0L 1NE LIOHTTNO PROFILE TLLUKTNATrCJN LEVEL AROUND MAINFRAME 

ILLUMINATION VALUES REPRESENT CUMULATIVE RAM FOOTCANDLES- NO MAINTENANCE FACTOR MAS' USED 



"LP # S/N X-LOC" Y-LOC HEIGHT ELEV AZIMTH LP-FACTOR IV "R-VALUE LAPIP DESCRIPTION 



1 1237 22 00 30.00 20.00 28.00 230 00 1.00 

2 1207 22.00 48.00 20.00 2B. 00 130.00 1.00 
"3 1237 52.00 30.00 20.00 28.00 300.00 1.00 

4 1207 96.00 51.00 22.00 22.00 30.00 1.00 

"-I* — -tOT "4T.30 90.00 22.00 30.00 180.00 1.00 



10. 63 SF.S-EA-400. COATED UPS" LAMP" | 

10. 63 SAME AS LAMP ABOVE 

10. 63 SAFE AS LAMP ABOVE - ! 

8. 89 SAKE AS LAMP ABOVE 

12. 70 HI75RDXFL39-22 MERCURY VAPOR 



SCALE IN BOTH DIRECTIONS (I INCH - "B". 0""FT7T " "" 

24. O 32. 40. 43. 3 — 56". 3 64. 71. O" 8077$ 

T2:3 - -20.0" -r 23.3 "• 36.0" ' 44T0 T 52 O '"~ T "~(6070~~ "' ~~5B.~3 '" '" 76.15 » 84.0 



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3.6* 9:23 B. 49" 6.5V 6.73" V. 12 ~ 3; 3B 4 69 230 

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3rT2 9.T1 ■-- 1 9 .6 9 -21.73 T2.-T0 13. 33 22. 9 



4.23 2.48 1.43 



1.93 



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"3. 5* — 3. 32 16. 33 29. 20 "19. 43 



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2 38 



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3. 14 3. 75 



8 29 



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9.37 12 26 18.40 



4:3* 11.11 23. 30 



36: 0—-ir - - 
2.76 



7.33 18.02 29.93 



60. O— 




4.93 2 81 



-4.-19- 10.90 21.93 22.94 11.70 12.78 23.74 23.26 1 1 09 3.93 



-2*6 



»-. 06 12. 30 17.22 11.23 9.28 16.73 23.61 14.98 6.13 2.33 



6. 34 10. 33 



7.14 8.73 16.11 15.10 8.51 3.39 



72. 0~ • 

1. 71 



3.13 3.09 3 91 3.32 3*8 7.73 11.23 8.30 4.08 2.01 



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3 62 3 73 

m — » 

2. 23 2. 53 



3. 78 4 42 5.35 6. 00 



4.04 2.23 



2. 86 3. 47 3 37 3. 29 



2.21 1 35 



FIGURE 12. - Marion 184-M lighting profile around main frame. 



292 




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FIGURE 13. - Page 7-32 dragline photograph of ground clearance, 



293 

Marion - Type 7800 Dragline 

Draglines usually operate very close to the edge of the pit. As the 
bucket is brought up debris is left along the pit edge. This debris is occa- 
sionally struck by the tailpiece as it swings. To avoid lighting fixture 
damage under the broad tailpiece of the Marion 7800 dragline, the lighting 
fixtures were placed closer to the tub. These fixtures were aimed at the tub 
to avoid blinding someone walking toward the machine. This light fixture 
placement resulted in a low illumination level under the rear of the main 
frame, but provided reasonable seeing conditions. 

LIGHTING SYSTEM INSTALLATION AND INITIAL EVALUATION 

The first task of Phase II was the installation of lighting equipment on 
each dragline. This was accomplished by mine personnel or contractors in 
accordance with the appropriate lighting system design plan discussed in the 
preceeding section of this report. All lighting fixtures were mounted and 
located as close as possible to the intended position determined by the "CALL" 
program studies. Individual location changes and/or discrepancies are dis- 
cussed under the appropriate dragline heading in this section of the report. 
All lighting fixtures were aimed using the coordinates indicated in the "CALL" 
program studies . 

As the second task of Phase II, photometric data were taken as the light- 
ing installations on each dragline were completed. Photometric data were taken 
at 0.76 m (30 in.) above ground level around the main frame of the dragline by 
swinging the machine into a desired position relative to a prepared grid 
matrix of 3.1 m (10 ft) squares. Photometric readings were taken at the 
corners and centers of each square. These data were presented on photometric 
layouts for ease of comparison to the initial calculated data for each drag- 
line. The initial average footcandle and uniformity ratios were calculated 
from the measurements taken and were presented on photometric layouts for each 
dragline. This paper presents the details for only the 184-M dragline as 
being typical of all three. Unique features or problems for the other two 
draglines are discussed. 

Marion - Type 184-M Dragline 

The results of the photometric measurements taken on the Marion Type 
184-M dragline are presented in Figures 14 and 15. A comparison of the design 
lighting levels under the main frame shown in Figure 8 and the initial 
measured lighting levels shown in Figure 14 indicates actual levels much lower 
than originally estimated. This is a result of light blockage by the crawlers 
and the contour of the underside of the main frame. As the main frame swings, 
the position of the two lighting fixtures under the main frame relative to the 
crawlers changes and so does the resulting light blockage by the crawlers. 
Thus the ground level illumination under the rear of the main frame is vari- 
able depending on machine position. The actual light level provided under the 
rear of the main frame was considered adequate for the functional tasks to be 



294 



WALKWAY ON LEFT 
SIDE OF MAIN 
FRAME 




LUX (FOOT- CANDLE) 

WALKWAY AROUND 
GANTRY 



.312.0 

(29.0) 



333.6 

(3-1 .0) 






8.4 
o) 



204.4 

(19. 0) 




10.8 15.. 

(l.O) (L-4.) 

19.4 33.6 26.9 

(l.S)(3. \)(2. S) 

• • • 

15.1 15. 



UNDER MAIN FRAME 



Roof Level 



23.7 

(2.2) 



68.9 



33.4 



19.4 
O.s) 



29. 



39.9. 
:i3.o) 



193.7. 

08.0)" 



129. , 

Cl2.Q) 



365.8 

C34-.0) 

247.5 

(23.Q) 



182.9 



(3.1) 



(2.7) 



( I 7.0) 



FIGURE 14. - Marion 184-M initial footcandle readings 



295 




296 

performed in this area. The vertical walls of the tub and crawlers were well 
illuminated because of the low mounting height of the fixtures. 

A comparison of the design lighting levels on the main frame roof shown 
in Figure 9 and the initial measured lighting levels shown in Figure 14 indi- 
cates lower levels at the rear of the main frame and higher levels at the 
front of the main frame. The lower lighting levels at the rear of the main 
frame resulted from the greater than 50 percent estimated blockage caused by 
the gantry catwalk. Increasing light levels in this area would require addi- 
tional lighting fixtures on or under the gantry walkway. The higher lighting 
levels at the front of the main frame are caused by spill from the 1000 watt 
lighting fixture used for boom walkway illumination. 

A comparison of the design lighting levels shown in Figure 11 and the 
initial measured lighting levels shown in Figure 14 indicates reasonable 
agreement . 

Figure 15 presents the light level readings around the main frame, under 
the boom and along the boom walkway. A comparison of Figure 10 and 15 indi- 
cates reasonable light level reading results except up near the end of the 
boom walkway where readings very close to individual fixtures causes discrep- 
ancies. As shown in Figure 15, light level readings 0.76 m (30 in.) above 
ground level under the boom centerline were well in excess of the require- 
ments. A comparison of the estimated and actual light levels, Figure 12 and 
Figure 15, indicates reasonable agreement except within a few feet of the main 
frame. This condition was caused by mounting the fixtures with the mounting 
frame down instead of extended. The result was light blockage of the beam 
pattern directly below each fixture. Average light level calculations around 
the main frame are presented in Figure 16. Since this was the smallest of the 
draglines evaluated, the lighting around the main frame was designed to mini- 
mize the number of lighting fixtures. This resulted in a small area on either 
side of the dragline having light levels below the minimum requirements. 

Page 7-32 Dragline 

The results of the photometric measurements taken on the Page 7-32 drag- 
line were as anticipated except for blockage by machine components and oper- 
ator reaiming of one lighting fixture directly above the operators cab. This 
was done by the operator to reduce glare and resulted in light levels below 
the requirements on the operators side of the machine. 

Marion - Type 7800 Dragline 

The results of the photometric measurements taken on the Marion 7800 
dragline were as anticipated except for minor discrepancies due to light 
blockage by machinery components. In general the required footcandle levels 
were provided or exceeded. 



297 















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298 

FINAL LIGHTING SYSTEM ADJUSTMENT AND EVALUATION 

Phase III of the project involved taking final light level readings on 
each dragline approximately three months after the lighting system instal- 
lation and initial evaluation. The final readings were taken to determine the 
effect of changes made to correct lighting system deficiencies, to detect any 
unanticipated radical changes in light levels, to assess the damage incurred 
to lighting system components, and to collect follow-up comments from each of 
the operators. Before taking final photometric readings, each dragline light- 
ing system was modified to correct deficiencies that became evident during 
the system installation and initial evaluation. The modification included 
adjusting lighting fixture aiming points, adding visors, and installing addi- 
tional lighting fixtures. Individual changes made to each dragline lighting 
system are discussed under the appropriate dragline heading in this section of 
the report . 

Final photometric data were taken as discussed in the preceeding section 
of this report. Readings were taken at roof level, along walkways, along 
ladders, and around the main frame. These data were presented on photometric 
layouts for ease of comparison. The final average footcandle and uniformity 
ratios were calculated from the measurements taken. 

Marion - Type 184-M Dragline 

At the time of final inspection both the dragline and the lighting fix- 
tures had operated 2,450 hours. During this period one 1000 watt high 
pressure sodium lamp was replaced after three days of operation. The second 
lamp operated for approximately one month and was replaced when the ballast 
failed and was changed. A third lamp was installed at that time and had been 
operating for over five months without failure. 

One 400 watt high pressure sodium lamp required replacement within the 
observation period. We do not know its service life. Two incandescent lamps 
placed on the boom survived less than one week. The fixtures housing these 
incandescent lamps were demolished a short time later. These lighting fix- 
tures were located in an exposed area close to the cables supporting the boom. 
The support cable movement was enough to reach and destroy the fixtures. No 
attempt was made to relocate these two fixtures closer to the walkway because 
the hoist rope cable for the bucket ran along the walkway. Heavy protective 
cages would be required for fixtures to survive in this location. 

One 480 volt 400 watt high pressure sodium ballast failed after 750 hours 
of operation. This ballast was returned to Phoenix Products Company and then 
forwarded to the ballast manufacturer. Inspection revealed a burned coil. 

One 1000 watt ballast operated for approximately one month before 
failure. The replacement ballast did not operate the lamp. A third ballast 
was installed and the lamp operated properly. The 1000 watt ballasts were 



299 

scrapped or lost at the mine site and the cause of failure could not be 
evaluated . 

Page 7-32 Dragline 

At the time of final inspection the Page 7-32 dragline accumulated 
590 hours of operation and the lighting system 95 hours of operation. During 
this period no lamp or ballast failures occurred. On four of the boom mounted 
fixtures a mounting bolt was not tightened properly. Tightening corrected 
this error. A lack of stiffness was also noted in three isolators of the 
SRS-100M fixtures. Examination of the isolators revealed that some of the 
mounting .bases had been welded to the supporting angle iron instead of bolting 
as intended. The excessive heat generated by welding damaged part of the 
rubber isolator pad allowing excessive movement of the light fixture head. 
The damaged isolator pads were replaced. 

The results of the final photometric measurements taken on the Page 7-32 
dragline lighting system were in compliance with the requirements except for 
certain walkways discussed in the following section of this report. 

Marion - Type 7800 Dragline 

At the time of final inspection the Marion Type 7800 dragline accumulated 
2,200 hours of operation and the lighting system 1,665 hours of operation. 
During this period, one 1000 watt high pressure sodium lamp failed and was 
replaced. No other lamp failure occurred during the evaluation period. 

The 480 volt 400 watt high pressure sodium ballasts failed and were 
returned to Phoenix Products Company. The first ballast failed to start and 
operate a lamp when first installed and was replaced. Inspection of this 
ballast by the manufacturer revealed a defective triac in the starting cir- 
cuit . The second ballast accumulated several hours of operation before 
failure. This ballast was not returned to the manufacturer for failure 
analysis because it was lost by the operator. 

The final photometric readings were in accordance with the required foot- 
candle levels except at the top end of the boom. This unique lighting problem 
is discussed in the following section of this report. 

OBSERVATIONS, COMMENTS, AND DISCUSSION 

The objective of this effort was to determine the feasibility of lighting 
draglines to the Proposed Mandatory Safety Standards. These Proposed Manda- 
tory Safety Standards were published in the January 13, 1977 "Federal Regis- 
ter" by MSHA as proposed regulations to CFR 77.207. In performing this task 
substantial effort was made to provide illumination as specified in CFR 
77.207, paragraph d, except items 1 and 2 (interior walkways and other 
interior areas) which were specifically excluded by the contract. The 
proposed regulations are summarized in Figure 1. 



300 

A review of the data indicates the technical feasibility of illuminating 
most of the specified areas on and around draglines, in accordance with the 
proposed regulations, by the systematic design and application of commercially 
available lighting equipment. In most instances the lighting systems evalu- 
ated were well received by mine operators and dragline personnel. Practical 
problems encountered are discussed below by the specific areas of the dragline 
requiring illumination in the proposed regulations. 

Illumination Around Main Frame 



Illuminating the area 6.1m (20 ft) around the main frame presents no 
major technical lighting system design or installation problems. However, 
measuring the light levels in accordance with the requirements was very diffi- 
cult in some instances. Draglines used in this demonstration operated on 
retreating ledges alongside the pit. This resulted in two sides of the 
machine — regardless of its rotational position, always being at the pit edge. 
There was not enough room around any of the machines to layout the complete 
grid system required for light measurements on the corners and centers of 
every 9.3 m 2 (100 ft 2 ) area. It was necessary to layout the grid system on 
only one side of the machine and then measure those light levels. The machine 
was then rotated to a new position and the process of grid layout and light 
level measurement repeated . 

While taking one set of readings, the Marion Type 184-M dragline operated 
at the end of a retreating ledge with the pit along one side and the spoil 
pile along the opposite side. Spoil was being discharged at the maximum dump 
height of the dragline and then pushed back by a dozer. The result was a very 
high, steep spoil pile with its base less than the necessary 6.1 m (20 ft) 
from the main frame. This meant climbing over spoil a short distance to get 
6.1 m (20 ft) away from the dragline for light readings. The close proximity 
and height of the spoil pile provided a huge reflective surface resulting in 
higher light level readings than would have been measured if the spoil pile 
were not present. It presented a hazard from tumbling rocks and slides to 
personnel taking the light readings. Under the proposed regulations, illumi- 
nation of the spoil pile is not required. 

Taking a complete set of light level measurements around the main frame 
in accordance with the proposed requirements will be difficult, time con- 
suming, and could be hazardous to personnel under certain mining conditions. 
One possible alternate method for measuring the light levels around the main 
frame is to take two sets of readings. The first set to be taken at a dis- 
tance of no more than 0.9 m (3 ft) from the main frame and the second set at 
no less than 6.1m (20 ft) from the main frame. Both sets of readings would 
be taken parallel to the main frame side, 0.8 m (30 in.) above ground level, 
on a horizontal plane and at least every 3.1 m (10 ft) or a minimum of four 
evenly spaced readings on each side. The machine operator would rotate the 
machine to the most accessible position for taking the light readings. 
Average light levels and uniformity ratios would remain as proposed. A second 
possible alternate method for measuring the light levels around the main frame 



301 

is to set reading markers at 1.5 m (5 ft) spacings along a straight line 
projected through the center of rotation of the machine. Readings would be 
taken at 0.8 m (30 in.) above ground level starting at the marker closest to 
the main frame, but not under it. At 1.5 (5 ft) spacings five readings would 
be taken approximately the required 6.1 m (20 ft) from the dragline then the 
main frame would be rotated through a fixed angle, possibly 10 degrees, and 
another set of five readings taken. This process could be repeated until 
readings were taken completely around the machine. Average light levels and 
uniformity ratios would be calculated from adjacent sets of readings. 

Area illumination around the main frame was well received by both the 
mine operators and the operating personnel for each dragline. The two excep- 
tions were machine operator complaints. Light sources mounted on the boom or 
main frame with the source light visibile from the operators cab caused dis- 
ability glare. Light sources placed in close proximity and especially 
directly above the operators cab caused veiling brightness in raining or foggy 
weather and when air born dust conditions were severe. This condition must be 
minimized by careful consideration of lighting fixture mounting and aiming 
during lighting systems design. 

Illumination Under the Main Frame 

Illuminating work or travel areas beneath the main frame presents design, 
installation, and light measuring problems. These problems result from the 
low ground clearance, the shape of the underside of the main frame and the 
physical restrictions resulting from the dragline tub and crawlers/ feet . 
Locations for mounting lighting fixtures under the main frame are very limited. 
Lighting fixtures must be located and mounted to assure protection from the 
debris at the pit edge which they are likely to strike when the machine 
rotates. Low ground clearance severely restricts the lighting system design 
in meeting the proposed requirements. Making light measurements in accordance 
with the proposed requirements is not only difficult when working in the 
confined space, but becomes impossible as the machine ground clearance 
approaches 0.8 m (30 in.). Laying out the grid system cannot be done in a 
standing position and taking light measurements 0.8 m (30 in.) from the ground 
can place the light meter closer to the machine underside than to the ground. 
The low fixture mounting height can result in the light meter being just a few 
feet from a lighting fixture. The result is uniformity ratios requirements 
could not be met. Under the conditions of low fixture mounting height and 
confined surroundings the vertical footcandle component of light present 
becomes important for the seeing tasks performed. This element of the light 
present is not evaluated by the current measuring method. 

One possible alternate method for measuring the light levels under the 
main frame is to take readings no more than 0.9 m (3 ft) underneath and 
parallel to the main frame sides. Measurements would be spaced no more than 
3.1 m (10 ft) apart with at least four readings on each side. The readings 
could be taken at ground level with the meter angled for maximum values. All 
readings should be no less than 53.8 Lux (5 ft-c) with the proposed average 



302 

intensity and uniformity requirements eliminated. A second possible alternate 
method for measuring the light levels under the main frame would be to extend 
the straight line/ rotating machine method discussed under Section A above 
under the main frame. Readings under the main frame could be taken at ground 
level with the meter angled for maximum values. The 53.8 Lux (5 ft-c) minimum 
requirement could be maintained if the proposed average intensity and 
uniformity requirements were eliminated. 

Illumination Along Walkways and Ladders 

In the effort expended on this project the requirements were interpreted 
to include ladders as walkways. Ladders and walkways present difficult light- 
ing problems. Walkways along the sides of the main frame require illumination 
because they are frequently traveled and often become storage areas for grease 
and oil cans, tool boxes, spare parts, rope, and chains. The required illumi- 
nation for these areas can be provided for by proper mounting and aiming of 
the area light fixtures mounted on the roof of the main frame. Walkways along 
the roof of the main frame can be illuminated from lighting fixtures mounted 
high up on the gantry. Walkways along the boom, except near the top can be 
illuminated by lighting fixtures mounted high up on the gantry. These geo- 
metrical situations present conditions suitable for the application of flood- 
lighting equipment to meet the required lighting levels. However, ladders and 
walkways near the top of the boom and around the top of the gantry present the 
physical restraints of low light fixture mounting height, limited mounting 
locations, and confined space. Illumination for ladders is required for 
safety. However, the proposed measurement method used for walkways illumi- 
nated by floodlighting cannot be applied to ladders. The rungs and handrails 
should be illuminated without shadowing caused by the person climbing the 
ladder. The proposed measurement method also eliminates the possibility of 
illuminating ladders and walkway gratings from below or behind. A solution to 
this measurement method problem might be to offer the option of using the 
proposed measurement method or an alternate method of measurement. The alter- 
nate method for measuring the light levels along walkways and ladders could be 
to take readings at the surface to be measured with the meter angled for 
maximum values. A 53.8 Lux (5 ft-c) minimum requirement could be maintained 
if the average intensity and uniformity requirements were eliminated. In 
discussions with mine personnel, it appears that certain walkways would not be 
used during night time hours. Routine maintenance of the boom is apparently 
limited to daylight hours. Perhaps exterior walkway lighting should only be 
required during periods when people are present. This modification of the 
requirements would reduce operator disability glare from boom mounted walkway 
lighting fixtures during digging operations of the dragline. 

Illumination Under the Boom 

With very few exceptions illumination beneath the boom will be in accord- 
ance with the proposed requirements on existing draglines involved in night 
time operations. Lighting beneath the boom in the pit is provided by boom 
mounted lights. The light levels required for normal production exceed the 



303 



10.7 Lux (1 ft-c) required for safety. However, boom mounted fixtures should 
be mounted and aimed so that direct source light is not visible to the drag- 
line operator in the cab. 

Illumination Along the Hoist Rope Line 

The proposed standards include no lighting requirements for illumination 
along the hoist rope line. However, every dragline operator expressed concern 
with the potential danger of pulling the hoist rope line knot through the 
point sheave severing the hoist rope line. Severing the hoist rope line 
certainly creates a hazard to operating personnel. The dragline operators 
ability to judge the maximum dumping height of the bucket and the relative 
position of the hoist rope line knot to the point sheave can be significantly 
improved by the application of lighting. Perhaps a minimum light level 
requirement perpendicular to the hoist rope line in the direction of the 
operator should be specified and a measurement method developed. 

CONCLUSIONS AND RECOMMENDATIONS 

As demonstrated by the test results of the lighting systems developed and 
evaluated under this effort, it is feasible to illuminate the specific areas 
on and around surface mine draglines in accordance with the proposed MSHA 
requirements by the systematic design and application of suitable lighting 
systems incorporating commercially available lighting equipment with the 
possible exception of some work or travel areas beneath the main frame, 
ladders, and certain walkways. It is impossible to measure the required light 
level at the specified 0.8 m (30 in.) from the surface to be measured beneath 
the main frame when the ground clearance is only 0.6 m (2 ft). The combi- 
nation of low lighting fixture mounting height and physically confined space 
tend to increase the importance of the vertical component of light necessary 
to be seen by a person outside the area and to perform the simple functional 
seeing tasks of self orientation and personal mobility. These same conditions 
of low lighting fixture mounting height and confined space also exist on some 
exterior walkways, catwalks, and ladders on the main frame and boom. Since 
the illumination under the rear of the main frame was adequate for functional 
tasks performed in this area including tending of a trailing cable, it is 
recommended that alternate methods of light measurement be evaluated for these 
areas including the possibility of angling the light-sensitive cell for the 
maximum reading at surface level. This method of light measurement would 
allow for illuminating ladders from behind and below. It would also provide 
for illumination of walkway gratings and safety railings from beneath. 

Under actual dragline mining conditions, measuring the light levels 
around the main frame in accordance with the proposed requirements was diffi- 
cult, time consuming, and exposed personnel to hazards presented by the spoil 
pile and pit edge. Additional effort should be made to develop a measurement 
method that would be safer and more practical under actual mining conditions. 
Spoil piles in the immediate vicinity of the machine should be illuminated. 



304 

Walkway and ladder illumination levels and measurement methods should be 
reviewed to determine the necessity for lighting requirements when personnel 
are not present and develop alternate methods of light level measurement more 
representative of functional seeing tasks. 

The dragline operators ability to judge the maximum dumping height of the 
bucket and the relative position of the hoist rope line knot to the point 
sheave can be significantly improved by proper illumination. Since severing 
the hoist rope line creates a hazard to operating personnel, requirements for 
illuminating the bucket and hoist rope line should be developed and included 
in the proposed MSHA regulations. 

High intensity discharge light sources were selected over incandescent 
light sources for most applications on surface mining draglines because of 
their high luminous efficacy, rugged shock and vibration resistant construc- 
tion, and long life. The frequency and amount of time expended servicing 
lighting equipment mounted on draglines is a major factor in the practical 
application of lighting systems to surface mining draglines. The use of a 
minimum number of rough service lighting system components capable of sur- 
viving in the environment is important to maintaining the light levels 
required on a long term basis. 



305 



TITLE OF PAPER: Lighting for Large, Mobile, 
Surface Mining Equipment 

AUTHOR: Martin H. Wahl 

Project Engineer 

Mine Safety Appliances Company 

Evans City, Pennsylvania 



Mr. Wahl, a Project Engineer in the Advanced Systems Division of Mine 
Safety Apppliances Company, received a B.S. Degree in electrical engineer- 
ing from the University of Pittsburgh. 

He designed and developed electromagnetic pumps for use with molten 
alkali metals. These designs evolved into a product line market by MSA to 
the liquid metals field. 

Mr. Wahl also directed and participated in the design and construction 
of large electromagnetic pumps for use by HEDL at Richland, Washington and 
Argonne National Labs at Idaho Falls, Idaho. 

Mr. Wahl directs in-house and commercial projects related to electrical 
engineering, and was responsible for conduct of this USBM-sponsored project 
to design lighting systems for lighting large mobile surface-mining 
equipment. 



306 



LIGHTING FOR LARGE, MOBILE, SURFACE MINING EQUIPMENT 

by 
Martin H. Wahl 1 



ABSTRACT 

This paper includes the design, installation, and demonstration of light- 
ing systems to meet the specifications of regulations proposed in Volume 42, 
No. 9, Section 77.207 of the January 13, 1977 issue of the Federal Register. 
Specifically, the demonstration was for the "Illumination of Electric Powered, 
Mobile Surface Mining Equipment" that included a 176 cubic yard dragline (B.E. 
3270), a 60 cubic yard dragline (B.E. 1450), and a 105 cubic yard shovel 
(Marion 5900). All equipment is owned by AMAX Coal Company, and is located 
in southern Illinois. 

Areas under the boom and around the main frame were designed to meet the 
minimum average illumination intensity of one (1) and five (5) footcandles (fc) 
respectively, at the specified uniformity ratio of 10/1. Operation of the sys- 
tem provided for a manual or automatic control, the automatic control being 
provided with a photoelectric device. 

Special mountings were constructed for installation of the luminaires on 
the machines. These mountings were designed to withstand the forces generated 
in the operation of a swinging boom and also to provide for ease of installa- 
tion. Attention was also given to the bulb supports to prevent a separation 
of the bulb and socket. 

High pressure sodium luminaires were used for the area illumination be- 
cause of the high output to watts ratio. The high pressure sodium replaces 
mercury vapor luminaires on the 60 cubic yard dragline and the 105 cubic yard 
shovel. The 176 cubic yard shovel was in the final stages of construction and 
utilized a mix of mercury vapor and high pressure sodium. 

Demonstration of the project extended over a period of three months, with 
a monthly visit to the sites to record operating data and personnel inter- 
views. The consensus of the mining personnel was favorable for use of high 
pressure sodium over mercury vapor lighting systems. One comment indicated 
work had proceeded through foggy periods where previous shutdowns had been 
required when mercury vapor lighting was used. 



Project Engineer, Mine Safety Appliances Company, Advanced Systems Division, 
Evans City, Pennsylvania. 



307 

ACKNOWLEDGEMENTS 

The work presented in this paper was authorized by the Bureau of Mines 
under a contract titled, "Illumination of Electric-Powered, Mobile, Surface 
Mining Equipment". Contract Officer is Alan Bolton, Contract Specialist 
William Mundorf and Tecbnical Project Officer William Lewis. The cooperating 
mine is AMAX Coal Company, Southern Division, with headquarters at Evansville, 
Indiana. Subcontractor for the design was General Energy Development Corpora- 
tion (GEDC) . 

INTRODUCTION 

The Federal Register Volume 42, Number 9, January 13, 1977, proposed rules 
for the illumination of draglines and shovels used in surface coal mining op- 
erations. An inquiry was issued for a study of "Illumination of Electric- 
Powered, Mobile, Surface Mining Equipment", to demonstrate the installation 
and operation of lighting systems designed to the specifications of the pro- 
posed rules. A contract was awarded to Mine Safety Appliances Company for 
this work. Specifically, the work reported here involves area lighting under 
the boom and around the main frame of the machines. 

Two draglines and one shovel were selected to participate in this project. 
They were the B.E. 1450, 60 cubic yards and B.E. 3270, 176 cubic yards, drag- 
lines located at the Delta Mine of AMAX and a Marion 5900, 105 cubic yards 
shovel located at the Leahy Mine of AMAX. A visit was made to the mines to 
observe on board operation of the machines, interview mine personnel, obtain 
layout drawings of each machine and to take photographs of each machine for 
reference during the lighting design stage. Some important machine informa- 
tion obtained for use in the design of the lighting systems is as listed in 
Table 1. 

Utilizing this machine information, a design format proceeded to select 
luminaires and specify mounting locations to provide illumination to the pro- 
posed rules. These illumination levels are shown in Table 2. 

LUMINAIRE SELECTION 

The design program was initiated with a review of existing lighting hard- 
ware available from a selected cross section of lighting equipment manufac- 
turers, in response to inquiries made for performance of the defined tasks. 
Selection of the luminaire for Area Lighting was based on sixteen criteria 
listed in Table 3. The rating of each luminaire was determined by a simple 
1 to 10 scoring system. 



308 



TABLE 1. - Mining Machinery Dimensions 

BUCYRUS ERIE 3270, 176 C.Y. DRAGLINE 

Boom Angle - 36° 

Boom Length - 330 feet 

Boom Height from Ground - 230 feet 

Operating Radius - 311 feet 

House Width - .116 feet 

House Length - 123 feet 

House Height - 60 feet 

MARION 5900, 105 C.Y. SHOVEL 

Boom Angle - 45° 
Boom Length - 210 feet 
Dumping Height - 130 feet 
Dumping Radius - 213 feet 
House Width - 60 feet 
House Length - 87 feet 
House Height - 80 feet 

BUCYRUS ERIE 1450, 60 C.Y. DRAGLINE 

Boom Angle - 38° 

Boom Length - 250 feet 

Boom Height from Ground - 170 feet 

Operating Radius - 227 feet 

House Width - 44 feet 

House Length - 90 feet 

House Height' - 30 feet 

TABLE 2. - Proposed Federal Standards 



Location 


Avg. 
FC 


Uniformity 
ratio 


1. All area 20' in all directions from the main frame, 
including all work or travel areas beneath the 


5.0 
5.0 

1.0 


10/1 
10/1 

10/1 


2. Exterior walkways on board draglines, shovels, and 
wheel excavators 


3. The area beneath the boom 20' from the main frame 
to the farthest point the equipment is capable of 
excavating or discharging material 







309 



TABLE 3. - Luminaire Selection Criteria 



1. Lamp Orientation 

2. Fixture Material 

3. Reflector Design 

4 . Mounting Method 

5. Light Source 

6. Lamp Replacement 

7. Photo Electric Controls , 

8. Low Temperature Starting 

9. Vibration 

10. Dust and Weatherproof ing 

11 . Ballasting 

12. Luminaire Angling , 

13. Standard Fixture Cost . . . 

14. Modification Cost , 

15. Time to Modify , 

16. Availability , 



Weight 



This 1 to 10 score, multiplied by the criteria weight resulted in the 
total weighted score for each manufacturer. Under this analysis, the GTE- 
Sylvania "Batwing" series of luminaires were selected for use in the Area 
Lighting. These luminaires were High Pressure Sodium (HPS) . 

LIGHTING DESIGN 

Mathematical models were constructed to deal with the problems relating 
to Area Lighting. The Mathematical Models for Area Lighting systems were de- 
veloped around the use of a computer programmed with all the pertinent infor- 
mation of the selected luminaires. There were six major data input areas nec- 
essary for the computerized mathematical models of the proposed area lighting 
systems. These were: 

A. Size of the machine to be illuminated by height, width, and 
length including separate boom angle specifications. 

B. Estimated heights at which luminaires are to be mounted. 

C. Type of luminaires to be used, including isointensity 
diagrams . 

D. Description of areas to be illuminated. 

E. Estimated luminaire layouts and aiming angles. 



Information on machine size and luminaire mounting heights was obtained from 
available drawings and photographs taken during visits to the AMAX mines. 



310 

The selection of luminaires was made, as previously discussed, based on com- 
parative evaluations of sixteen criteria, with the GTE-Sylvania high pressure 
sodium Batwing series scoring the highest evaluation points. The areas to be 
illuminated around the raining equipment were proposed by MSHA in the Federal 
Register and included: 

1. All areas 20 feet in all directions from the main frame. 

2. Area beneath the boom frame 20 feet from the main frame to 
the farthest point the equipment is capable of excavating 

or discharging material. The area for boom lighting was not 
definitive enough for an accurate computer input as relates 
to the distance on either side of the boom. The area under 
the boom was redefined to specify the width as equal to the 
main frame plus forty feet. 

The light loss factors were applied in three areas, as follows: 

1. Installation and manufacturing tolerance 5% loss 

2. Lamp lumen depreciation at 3/4 rated lamp life 15% loss 

3. Dirt accumulation on fixture 19% loss 

Total Light Loss 39% 

Estimated luminaire layouts and aiming angles were based on known tech- 
nology in establishing uniform distribution patterns for large area lighting 
installations. Horizontal and vertical aiming of individual luminaires were 
determined after analyzing computer printouts which had luminaires mounted at 
angles perpendicular to the ground. Horizontal and vertical aiming angles 
were modified with respect to set guidelines, uniformity ratios and average 
foot candle levels for the entire area illuminated. 

Utilizing the information available for these six major data input areas, 
the computer analyzed each point of the areas to be illuminated on a prede- 
termined grid pattern and then provided a printout of this information. The 
printout was compared with original estimates and the levels set for in the 
proposed MSHA regulations and adjustments were made, as required, to aiming 
angles, mounting location and height to determine the optimum illumination 
layout. With this iteration the computer again provides a printout listing 
the footcandles that can be expected in each area of the established grid sys- 
tem. An analysis of this printout will indicate whether too many or too few 
luminaires are being used and whether a higher or lower wattage luminaire 
would improve the quality of the illumination layout. 

Utilizing the mathematical models and the format described, illumination 
systems were designed for the machines. It was found that the optimum 



311 

illumination layouts utilized 1000 watt high pressure sodium luminaires for 
the B.E. 3270 dragline and Marion 5900 shovel and 400 watt high pressure sodi- 
um luminaires for the B.E. 1450 dragline. 

The B.E. 1450 required eleven 400 watt high pressure sodium luminaires 
to light the areas around the main frame and under the boom. Six of these 
luminaires were mounted on the roof and five on the boom. Nine 1000 watt high 
pressure sodium luminaires were required for the B.E. 3270 dragline. Three 
were mounted on the roof, two on the front of the house, and four on the boom. 
The Marion 5900 shovel required eight 1000 watt high pressure sodium luminaires, 
three on the roof, one on the front of the house and four on the boom. 

After approval of the designs, installation drawings providing location 
and aiming information were presented in an orientation at AMAX facilities. 
In addition, electrical diagrams provided information for wiring of the light- 
ing system. All systems utilized 480 volts for operation of the luminaires 
with a central electrical panel installed for control. Automatic dusk to dawn 
operation was arranged for by use of a photoelectric cell. 

DEMONSTRATION 

Design of a lighting system is only an orderly method of prediction of 
its operation, based on the application of available engineering information. 
The integrity of the design must be verified by accepted standards of tests 
and measurements. To perform these tasks a photometric survey procedure was 
developed. 

The program developed for this work included verification of the instal- 
lation according to design by checking: 

1. Mounting heights and distances 

2. Aiming angles 

3. Physical obstructions to the light patterns 

4. Operation of electrical controls 

To correlate the actual lighting designs with the installed systems, a 
portion of the ground under consideration was divided into test areas of the 
same grid setup as planned for the computer design printout. Readings were 
taken at each 10 ft. by 10 ft. grid area, with repeat measurements at a key 
test point with a frequency to assure stability of the system and repeatability 
of results. It was expected that the test readings would be much higher than 
the computer projections, since the lamps were new and the Light Loss Factor 
(LLF) of 0.61 not applicable. 

Two complete field photometric surveys were conducted on each machine. 
The first survey was made at the completion of the installation of the lighting 



312 

systems on each individual machine and the second at the end of the demonstra- 
tion period. It must be noted that the installation on each machine was con- 
tingent with the time the machine may be out of production due to scheduled 
or unscheduled maintenance. The B.E. 3270 dragline was a new machine in the 
process of being constructed, so the lighting system was installed prior to 
its completion. The B.E. 1450 dragline and the Marion 5900 shovel lighting 
systems were installed when the machines were taken out of production. 

The demonstration period was to be for three months, but was of different 
lengths of time because of the inability to install the lighting systems simul- 
taneously on each machine. The demonstration period started at the time of the 
first photometric survey and was considered complete at the time of the second 
photometric survey. The second photometric survey was performed on all ma- 
chines on the same date. 

ANALYSTS 

Analyses were made of the surveys to each other, to the Computer Mathe- 
matical Models (CMM) , and to the Proposed Federal Standards (PFS) . 

A review of the computer printouts for the various trace areas under the 
boom and around the main frame show that the average computer calculated foot- 
candles is greater than required by the Proposed Federal Standards. The com- 
parative averages for the specific machines are shown in Table 4. 

The above average CMM intensities in Table 4 were calculated high because 
they are expected to depreciate due to uncontrollable loss factors. These 
above average CMM intensities also represent the lighting produced from an op- 
timum luminaire selection which dictated that mixed lamp wattages within the 
system would not be advantageous toward long-term maintenance of the system. 

Field photometric survey No. 1 was conducted on each machine soon after 
the lighting systems were installed and operational. The comparative averages 
between the No. 1 photometric survey and the Computer Mathematical Model (CMM) 
for specific machines are shown in Table 5. Certain discrepancies can be noted 
in Survey No. 1 which are attributed to the inability to properly aim the lumi- 
naires, especially around the main frame of the machines. Obstructions and 
overhangs were encountered which were not evident in the review of machine 
drawings. For example, a 1000 watt high pressure sodium luminaire mounted on 
the side of the Marion 5900 had a light intensity of only 43 percent of the 
same luminaire mounted on the B.E. 3270 although the B.E. 3270 is a larger 
machine. This intensity can be increased by mounting the Marion 5900 main 
frame luminaires at lower points under any obstructions, although this may in- 
hibit the ease of maintenance of these fixtures. Multiple fixtures (placed at 
top corners) may be a more feasible solution. Areas under the boom of all 
three machines had higher average intensities than predicted by the CMM and 
considerably above the Proposed Federal Standards. 



TABLE 4. - Comparative averages 

Computer mathematical models (CMM) 
Proposed federal standards (PFS) 



313 



B.E. 3270 



Area 


Averag 
CMM 


e fc 
PFS 




3.2 

16.3 

8.3 

6.5 


1.0 


20' from main frame, 
20' from main frame, 
20' from main frame, 


front. . . 
side. . . . 
rear. . . . 


5.0 
5.0 
5.0 



B.E. 1450 



Area 


Averag 
CMM 


e fc 
PFS 




3.0 
9.8 
7.3 
7.2 


1.0 


20' from main frame, 
20' from main frame, 
20' from main frame, 


front. . . 
side. . . . 
rear .... 


5.0 
5.0 
5.0 



Marion 5900 



Area 


Averag 
CMM 


2 f C 

PFS 




3.4 

12.1 

7.2 

7.2 


1.0 


20' from main frame, 
20' from main frame, 
20' from main frame, 


front. . . 
side. . . . 
rear. . . . 


5.0 
5.0 
5.0 



314 



TABLE 5. - Comparative averages 

Photometric survey no. 1 
Computer Mathematical Model (CMM) 



B.E. 3270 



Area 


Average 
Survey no. 1 


fc 


CMM 




3.4 
14.2 
8.1 
(lumin. out) 




3.2 


20' from main frame, 
20' from main frame, 
20' from main frame, 


front. . . 
side. . . . 
rear. . . . 


16.3 

8.4 
6.5 



B.E. 1450 














Average 


fc 




Area 




Survey no . 1 




CMM 






5.3 




3.0 


20' from main frame, 


front. . . 


(not aimed) 




9.8 


20' from main frame, 


side. . . . 


4.0 




7.3 


20' from main frame, 


rear. . . . 


3.3 




7.2 



Marion 5900 



Area 


Average fc 
Survey no . 1 CMM 


20' from main frame, front... 
20' from main frame, side.... 
20' from main frame, rear.... 


4.0 3.4 
3.3 12.1 
3.3 7.2 
3.5 7.2 



315 



The second series of field photometric survey were conducted from four to 
eight months after the machines had been operating with the new lighting systems, 
The comparative intensity averages of the two photometric surveys, the Computer 
Mathematical Model and the proposed Federal Standards are shown in Table 6. 

TABLE 6. - Summary of comparative averages 

B.E. 3270 8 months of operation 



Average fc 



Area 


Survey 
no. 2 


Survey 
no. 1 


CMM 


PFS 




3.6 

15.5 

7.4 

3.2 


3.4 

14.2 

8.1 

N/A 


3.2 

16.3 

8.4 

6.5 


1.0 


20' from main frame, front... 
20' from main frame, side. . . . 
20' from main frame, rear.... 


5.0 
5.0 

5.0 



B.E. 1450 4 months of operation 



Average fc 



Area 


Survey 
no. 2 


Survey 
no. 1 


CMM 


PFS 


20' from main frame, front... 
20' from main frame, side. . . . 
20' from main frame, rear.... 


5.7 

N/A 

5.9 

(lumin. 

out) 


5.3 

N/A 
4.0 
3.3 


3.0 
9.8 
7.3 
7.2 


1.0 
5.0 
5.0 
5.0 



Marion 5900 



6 months of operation 



Average fc 



Area 


Survey 
no. 2 


Survey 
no. 1 


CMM 


PFS 


20' from main frame, front... 
20' from main frame, side. . . . 
20' from main frame, rear.... 


4.0 
1.9 
1.9 
4.8 


4.0 
3.3 
3.3 
3.5 


3.4 

12.1 

7.2 

7.2 


1.0 
5.0 
5.0 
5.0 



316 

Discrepancies noted in the second series of photometric surveys were similar 
to those experienced in the first surveys- Boom area readings, for example, 
on the B.E. 3270 in the second survey tended to average higher than the first 
survey. This may be attributed to the slight shifting of luminaires under vi- 
bration and shock. Point readings at the end of the boom were lower in the 
second survey, with a tendency for the light pattern to shift toward the main 
frame. Lamp lumen depreciation cannot be expected to have any measurable ef- 
fect after 8 months of operation, since the sodium lamps are rated at 24,000 
hours, which is equivalent to 2-3/4 years. 

Several luminaires experienced maintenance difficulties during the dem- 
onstration period and required replacement of lamps and brackets. It is quite 
possible that luminaire aimings were disturbed during this maintenance. This 
would appear to have happened with the front and side lighting on the Marion 
5900 which shows a degradation in light levels between Survey No. 1 and Survey 
No. 2. 

SUMMARY AND RECOMMENDATIONS 

The ability to meet the Federal Proposed Standards for area lighting ap- 
pear to be easily accomplished with the hardware now on the market. In fact, 
the photometric surveys showed that the average intensity under the boom area 
was better than three to five times greater than the Proposed Federal Stand- 
ards. Even applying a light loss factor of 0.61, the intensity would be two 
to three and one-half times as large as the Federal Proposed Standards. 

The results of the lighting systems installed for illumination of area 
around the main frame was less definitive. The Computer Mathematical Model 
predicted higher levels than were achieved, although the average levels were 
higher for the B.E. 1450 and B.E. 3270 draglines than the Proposed Federal 
Standards. However, the Marion 5900 shovel light levels were less than the 
proposed standards on all sides, except the rear of the machine. Apparently 
the luminaires used for lighting the main frame encounter difficult mounting 
locations. It appears that main frame lighting from a luminaire mounting and 
aiming standpoint is more complex than assumed, and must be defined in closer 
detail in order to result in a more effective system. 

We must note that although standard hardware was used for illumination of 
the large surface mining machines, they required modifications to qualify for 
the hostile services aboard the machines. These modifications were related to 
mountings and bulb supports to withstand the shock, vibration and unusual G 
forces encountered during the swing and excavation stages of the machines. 

The results of the lighting demonstration indicate that a Computer Mathe- 
matical Model approach can be an effective tool in designing lighting systems 
for electric-powered, mobile, surface mining equipment. The tangible results 
of the photometric surveys of the areas under the booms of the three machines 
demonstrate the feasibility of this approach. From an illumination standpoint, 
the luminaires are capable of providing more than enough light to meet the 



317 



Proposed Federal Standards for lighting around the main frame. However, be- 
cause mounting the luminaires on the machine roofs does encounter obstruc- 
tions, the mounting of these luminaires on the sides of the machines will re- 
sult in a better lighting pattern, but will do so at a sacrifice in the ability 
to provide maintenance to the fixture. 

This presentation has dealt with work involved in the design, installa- 
tion, and demonstration of lighting systems to a specification. The specifica- 
tion was proposed to provide a uniform set of standards that would result in 
a level of illumination that would enhance safety in the designated work areas. 
Other than the accumulation and statistical evaluation of long term data on 
the safety of an operation, the comments of the workers can serve as a gage 
for the operations. Some workers' comments received during field evaluation 
and interviews heartily endorse the illumination systems. A cross section of 
the comments are: 

1. Wouldn t be without the new system. The new system prevented 
a couple of shutdowns due to fog. 

2. Looks like a graveyard without. Didn't think new system 
would make any difference, now wouldn't go back to old 
system. Dust is more of a problem with old system. (Old 
system is mercury vapor.) 

3. No difficulty with new system, adds a lot of light. Not 
safe without side and rear lights. Good light in pit. 
Can't get too much light. New system is a lot safer. 
Old system is not safe by itself. 100% improvement. 



4. The lights have been on all the time. The operators think 
they can't run without the new lights. The project has 
been worthwhile. 

5. Helps with fog. Crews like them. 

If the working conditions of large mobile surface mining equipment can 
be improved, then we must assume that safety is improved. Along with im- 
proved working conditions, the flip side can mean increases in productivity. 
Increased safety and productivity are hypothesized due to adequate levels of 
lighting. We feel the long term records will verify this assumption. 



318 



TITLE OF PAPER: Definition of Illumination Requirements for 
Underground Metal and Nonmetal Mines 



AUTHOR: WILLIAM H. CROOKS, Ph.D. 

Group Director, Engineering Psychology Group 
Perceptronics , Inc. 
Woodland Hills, California 

James M. Peay 

Engineering Psychologist 

U.S. Bureau of Mines 

Pittsburgh Mining and Research Center 

Pittsburgh, Pennsylvania 



This paper was not presented at the conference since the program stressed 
underground coal mines. However, the paper is included in the proceedings 
because some of the principles described, although intended for metal, non- 
metal mine applications, may be potentially useful to coal mine operators. 



319 



DEFINITION OF ILLUMINATION REQUIREMENTS FOR 
UNDERGROUND METAL AND NONMETAL MINES 1 , 2 

by 

William H. Crooks 3 
and 
James M. Peay* 4 



ABSTRACT 

This study presents the analysis of underground work areas and tasks for 
the purpose of identifying the illumination characteristics of underground 
metal and nonmetal mines in the United States. Attention is given to the 
visibility requirements of underground jobs and to the illumination and re- 
flectance characteristics of underground work areas. Attention is also given 
to identifying the number of people performing underground tasks and the acci- 
dents that occur to those underground workers. Experimental evaluation of 
visual task performance under varying levels of illumination lead to recom- 
mendations for minimal luminance levels in underground metal and nonmetal 
mines. The final result of this research leads to practical recommendations 
for improved underground lighting practices. 

INTRODUCTION 

The importance of good lighting to the underground miner cannot be over- 
emphasized. In addition to the obvious benefits of improved worker morale, 
available studies (Trotter, 1977) have shown that good lighting reduces acci- 
dents and increases productivity. However economics will not allow the gen- 
eral level of lighting in a mine to approach the levels found in most factory 
worksites. Therefore, the light levels used in underground mines should be 
based upon the minimal luminance levels necessary for safe performance of 
critical mining tasks. 

^his research was supported by the U.S. Bureau of Mines under Contracts 
J0387230, and J0319022. 

2 The views and conclusions contained in this document are those of the authors 
and should not be interpreted as necessarily representing the official poli- 
cies or recommendations of the Interior Department's Bureau of Mines or of the 
U.S. Government. 

3 Group Director, Perceptronics , Inc., Woodland Hills, California 

^Engineering Psychologist, U.S. Bureau of Mines, Pittsburgh, Pennsylvania 



320 

The basic research needed to establish minimal luminance requirements for 
safe job performance in underground coal mining was performed by Hitchcock 
(1973). This research identified the required minimal luminance levels for a 
number of visual tasks associated with mining jobs in both conventional con- 
tinuous and longwall coal mining methods. From the findings of this research, 
a common minimal luminance level was specified for all underground coal 
mining . 

Initial consideration of the illumination needs of workers in underground 
metal and nonmetal mines would suggest that adoption of the coal mining lumi- 
nance levels would be sufficient. Certainly miners in metal and nonmetal 
mines work in similar conditions to those in coal mines. That is, miners in 
both types of mines typically work in confined spaces with only a cap lamp 
providing illumination. However, closer examination quickly reveals major 
differences between coal mines and metal and nonmetal mines. The greater 
variety of mining methods in the latter industry suggests a greater variety of 
jobs as well as a greater variety in the size and configuration of the working 
spaces. In addition, the wide variety of commodities extracted by metal and 
nonmetal miners suggests a wider range of reflectances of the underground 
surfaces than would be found in coal mining. 

In light of the apparent differences between coal mining and metal and 
nonmetal mining, the U.S. Bureau of Mines has embarked on a program of re- 
search to identify the specific illumination characteristics of underground 
metal and nonmetal mines (Crooks, et al ; 1980). The focus of this research is 
on the underground work locations and worker activities where the intent has 
been to identify the illumination needs of the work locations and activities. 

The objectives of the research are (1) to identify the illumination 
characteristics of underground jobs and work locations, (2) to identify the 
visual tasks of underground jobs, (3) to specify minimal luminance require- 
ments for safe work, and (4) to suggest improvements for safety in metal and 
nonmetal jobs and work locations. 

ANALYSIS OF UNDERGROUND WORK AREAS AND TASKS 

This study includes analyses of six distinct but closely related matters. 
The first analysis considered the underground locations where miners perform 
their jobs. This analysis included identification of the major categories of 
underground work locations within metal and nonmetal mines, followed by de- 
tailed on-site observations and evaluation of a carefully selected sample of 
work sites. Illumination, sound, and atmospheric measurements were made and 
the number, type, and locations of luminaires and mining machines were identi- 
fied at each location. In addition, the work activities being performed at 
the location were identified. This analysis of work locations provided the 
basis for the comprehensive description of the illumination characteristics of 
underground work locations in metal and nonmetal mines. 

The second analysis of the study concerned the illumination and visi- 
bility characteristics of the rocks and minerals that constitute the majority 



321 

of the surfaces found in the mines. A Mine Illumination Laboratory was used 
to determine the directional light distribution ( goniophotometric) properties 
of samples of rocks and minerals from a wide variety of metal and nonmetal 
mines. This laboratory (1) allowed the time necessary for detailed gonio- 
photometric measurements and (2) provided the highly accurate instruments 
required for these measurements. Analyses of these goniophotometric charac- 
teristics provided the basis for identifying the reflectances that are encoun- 
tered in metal and nonmetal mines. 

The third analysis of this study focused on the jobs that underground 
workers perform in this industry. The intent of this analysis was to identify 
the specific tasks that are performed by the various workers, especially those 
tasks that are impacted by the illumination present in the underground work 
locations. Through both on-site observations of work activities and struc- 
tured interviews with experienced miners, the tasks and activities that con- 
stitute the underground work operations were identified. 

The fourth analysis of the study focused on the accidents occurring in 
underground metal and nonmetal mines and on the employment distribution across 
this industry. The focus of this latter analysis was to identify the number 
of people performing the various underground tasks and the accidents that 
occurred to those underground workers . 

The fifth analysis concerns the visual tasks that are associated with the 
underground work activities. The purpose of this analysis is first to iden- 
tify the visual tasks and then to determine experimentally the lowest lumi- 
nance under which the visual tasks can be performed. 

The product of the sixth analysis is the recommendations for minimal 
luminance levels in underground metal and nonmetal mines. The final analysis 
is a synthesis of the results from the five previous analyses, plus results 
from other research studies and standards of industrial illumination. 

We now turn to a discussion of the specific conclusions that may be drawn 
from the analyses performed to date. 

THE UNDERGROUND WORK ENVIRONMENT 

Analysis of the underground working environment suggests that the cate- 
gories of work locations shown in Table 1 constitute a useful taxonomy of work 
stations that encompass the vast majority of underground work areas in metal 
and nonmetal mining. 

With regard to illumination, analyses of the underground work environment 
indicate that although some general similarities exist, there is great varia- 
bility in the many characteristics of work sites in underground metal and 
nonmetal mining. This variability exists both between different mines and 



322 

within a given mine. In general, we found that underground work environments 
differ significantly in surface luminances and reflectances, output of lumin- 
aires and types of visual impairments that are present. 

Production and development sites have lower reflectance, lower output 
luminaires, lower luminances, and are more likely to have visual impairment 
due to aerosols or hydrosols, than do permanent work sites such as ore trans- 
fer and processing stations and maintenance shops. Additionally, production 
and development sites are characterized by a significant number of visual 
impairments, of which direct glare and the scattering of light due to the 
presence of aerosols and hydrosols appear to pose the greatest problems. 
Aerosols and hydrosols often obscure the face, and the scattering of light 
reduces apparent luminance. 

Three-fourths of all work sites measured have surface reflectances of 
less than 30%. Reflectance varied significantly among the measured mines. 
Direct glare from light sources is a problem when the operator must work 
between luminaire and task, when luminaire design is poor (e.g., bare lamps), 
or where two or more workers are in close proximity and glare from cap lamps 
becomes a problem. 

There are also significant differences in the sizes of the openings, 
ranging from 4' x 4 1 x 10' development raises to 125' x 200' open stopes. The 
height of most underground work locations is relatively uniform, with a median 
of eleven feet. However, the width and depth of these locations varies 
greatly between mines and within some mines. These variations in size of 
openings are positively correlated with the luminances of the surrounding 
area, probably due to the higher output luminaires generally used in the 
larger openings. 

Perhaps the most significant finding regarding the work environment is 
the wide variety of operations performed in any given work site. As we will 
suggest, the work activity being performed, rather than the work site itself 
should be the primary focus of any illumination standards for underground 
metal and nonmetal mines. 

TABLE 1 . - Categories of underground work locations 

Production sites Haulage sites 

. Faces . Loading sites 

. Stopes . Haulage ways 

. Dump sites 
Development sites . Skip pockets 

. Faces 

. Exploration Ore processing sites 

. Construction 

Miscellaneous sites 
. Shaft landings 
. Maintenance shops 



323 

REFLECTANCE OF METAL AND NONMETAL ROCKS AND MINERALS 

There is no single number that fully describes the reflectance of a 
surface. For above-ground applications, the use of a single reflectance 
obtained from a standardized geometry is an acceptable approximation for 
painted walls or carpeted floors. But the situation underground is far more 
complex. The directional light distribution (gonioref lectance) of rocks and 
minerals varies with the source angle, angle of view, presence of dust or 
water, and the reflecting characteristics of the surface. The range in gonio- 
ref lectance for any given sample can be tremendous. The ratio of highest to 
lowest gonioref lectance can be more than 10:1 for shale or sphalerite and as 
little as 2:1 for dolomite. Water is a major contributor to the variance for 
most rocks and minerals. At most viewing angles, water causes a 25% to 50% 
reduction in the gonioref lectance but the complimentary angle can increase the 
gonioref lectance , in some cases to over 100%. Surface moisture can be a 
significant source of reflected glare if the wet areas are sufficiently large. 
(The surface must also be brightly lit and the operator at the complimentary 
angle position.) 

Compound reflection types are illustrated in Figure 1. Most dry rocks 
and minerals are matte diffuse reflectors and when wetted become diffuse and 
spread reflectors. A few become diffuse and specular reflectors when wet and 
are the most likely to cause visual impairment due to reflected glare. Gunite 
and white wash are diffuse reflectors which may be used to improve the visual 
environment . 

Most mines are in a single major rock or mineral type (whose gonio- 
ref lectance, however, may be highly variable). A few mines have several major 
rock or mineral types present. If these types are significantly different in 
gonioref lectance , that mine will face tremendous difficulties in providing the 
optimal amount of illumination for any given task. Using the gonioref lectance 
data shown in Figure 2, the lighting that is adequate for development activ- 
ities in dry dolomite will have to be increased approximately 400% to achieve 
the same luminance levels for production work in wet sphalerite. Or, if the 
equipment lighting is designed to provide adequate luminance production in wet 
sphalerite (worst case) , more illumination will be provided than is cost- 
effective or necessary at other work sites. 

The range of gonioref lectances found within a given mine also has impli- 
cations for the enforcement of minimal luminance standards. For example, a 
jumbo drill with a given set of luminaires could be in compliance working in 
dolomite or feldspar and out of compliance in sphalerite or shale at the same 
mine. The differences among rock and mineral types are such that it may be 
cost-effective to tailor equipment lighting systems to particular gonio- 
reflectance ranges. 



324 




Matte diffuse 



X /<] 


r? 


y7/) 


w 


// 


// 


^ 


k 


<y& 




Diffuse and spread 



Diffuse and specular 



FIGURE 1. - Examples of types of reflection observed in the mining 
illumination laboratory. 



Mean wet 
Dolomite 

Lower bound 
Sphalerite 



Mean dry 
Dolomite 



Source 




101 MB 



100 m u m 



FIGURE 2. - Estimate of the mean gonioref lectance of faces at a single 
mine (source angle 120°). 



325 



UNDERGROUND WORK ACTIVITIES 



During the course of the current research, we determined that the typical 
classification of work activities according to job title would not be useful. 
Analysis of a large sample of job titles revealed that many persons holding 
different job titles perform the same work activities. Conversely, people 
having the same or similar job titles often perform entirely different work 
activities. Accordingly, we chose to consider the unit operations being 
performed. Analysis indicated that the vast majority of work activities in 
metal and nonmetal mining are encompassed by the unit operations listed in 
Table 2. 

TABLE 2. - Categories of unit operations 



DRILLING 

Jackleg Drilling 
Raise Drilling 
Jumbo Drilling 
Stoper Drilling 
Ring Drilling 
Rotary Drilling 

GROUND SUPPORT 

Rock Bolting 
Tlnber Post Erection 
Gunnlte/Shotcreting 
Tlnberset Assembly 
Cribbing 
Sandfllllng 
Preparing Wort Area 

LOADING 

LHD Operation 
Slusher Operation 
Overshot Loader Operation 
Manual Shoveling 
Chute Pulling 
Ga the ring-Am Loader 
Operation 



HAULAGE 

Train Operation 
Truck Operation 
Shuttle Car Operation 
Conveyor Operation/ 

Maintenance 
Tugger 

MAINTENANCE 

Shaft Maintenance 
Machine Maintenance 
Roadway Maintenance 
Track Maintenance 

SERVICES 

Pipe Installation/Repair 
Ventilation Control 

Instal 1 at1 on/Repa 1 r 
Electrical Installation/ 

Repair 

CONSTRUCTION 

Concreting 

Steel Construction 

Timber Construction 



BLASTING 

ANFO Loading/Blasting 
Stick Powder Loading/ 
Blasting 

EXPLORATION 

Diamond Drilling 

Surveying 

Sampling 

CONTINUOUS MINING 

Continuous Miner Operation 
Cutter Bar Operation 

HOISTING 

Man Cage Operation 
Ore Skip Operation 

SUPERVISION 

Supervising/Coordinating 

Workforce 
Safety Inspecting 

UNDERGROUND ORE PROCESSING 

Ore Crushing 



Although we analyzed many aspects of the unit operations performed by 
underground workers, including physical demands, training requirements, and 
time requirements, we focus here on the unit operations with inherent exposure 
to risk and. with high visual demands placed on the worker. It will be seen 
that these activities are also critical in terms of productivity. By these 
criteria, the critical unit operations are: 



Feed drilling 
Jumbo drilling 
Rock bolting 
Preparing work area 
L.H.D. operation 
Slusher operation 
Manual shoveling 



Train operation 

Conveyor operation and maintenance 

Machine maintenance 

Pipe installation and repair 

ANFO loading and blasting 

Stick powder loading and blasting 

Safety inspecting 



326 

The visual abilities most frequently required in the performance of the 
aforementioned tasks were: depth perception (72%); accommodation (64%); far 
acuity (43%); near acuity (36%); peripheral vision (36%); and color discrim- 
ination (7%). From this listing, it is evident that some critical tasks make 
very low demands upon the visual system, while others may require the exercise 
of several visual capabilities in concert. Manual shoveling, for instance, 
can seemingly be performed satisfactorily under visually disadvantageous 
conditions, while jumbo drilling, L.H.D. operation, work site preparation, 
loading and blasting, and safety inspection bring into play the full spectrum 
of visual discrimination potential. One may conclude, therefore, that certain 
of these critical operations should be done by trained personnel with intact 
visual systems if safety and productivity criteria are to be met. 

Our analyses have also shown that workers' ratings of the relative 
degree-of-hazard inherent in a unit operation is significantly and inversely 
correlated with the amount of luminance associated with that operation. 
Further, the accidents occurring in specific unit operations are inversely 
correlated with the amount of luminance. In other words, those unit oper- 
ations that are perceived as being hazardous, and that do have higher than 
average numbers of accidents, are often performed in areas with lower lumi- 
nance levels. 

Moreover, our analyses indicate that there is currently no apparent rela- 
tionship between the type of luminaire typically used for a unit operation and 
the visual demands of that operation. Unit operations with frequent visual 
demands were just as likely to use only cap lamps as to use high-output types 
of luminaires . For operations requiring near acuity, the cap lamp is probably 
quite sufficient. However, the lack of relationship between luminaire type 
and visual demand should attract attention when considering unit operations 
requiring far acuity, depth perception, and wide fields of view. 

CRITICAL MINING ACTIVITIES 

We now turn our attention to accidents associated with the critical 
underground work activities. For purposes of this discussion, "critical" 
mining activities are defined as those unit operations that are associated 
with a high accident index. Our analysis indicated that those unit operations 
with the highest accident indices are concentrated in the drilling, ground 
support, haulage, and loading categories. A significant number of these 
accidents is associated with nonpowered hand tools, which points up the 
importance of taking a closer look at the design of these types of tools for 
use by underground mining personnel. Another important finding was that of 
all worker activities, "barring down" or "scaling" accounts for the largest 
percentage of deaths or fatalities in the underground metal and nonmetal 
mining industry. Thus, it is advised that particular attention be given to 
the tools, procedures, and illumination associated with that unit operation if 
the number of underground fatalities is to be reduced. 



327 

We stress, however, that although the accident index may highlight some 
unit operations as being particularly accident prone, serious attention must 
also be given to those unit operations which account for a large overall 
number of accidents. For example, maintenance has an accident index of 1.0, 
indicating that the "exposure" rate of accidents for that operation is aver- 
age. However, because maintenance is such a widespread activity, 13 percent 
of all underground accidents in metal and nonmetal mining is associated with 
maintenance. Thus, efforts aimed at reducing maintenance accidents will go a 
long way toward reducing the number of people who are hurt every year. 

ENVIRONMENTAL VARIABLES AND ACCIDENTS 



The preceding sections have summarized many variables that are presumed, 
on the basis of an array of statistical analyses, to be related to general 
safety in the underground environment . These include various types of lumi- 
nance measurement, luminaires, hazard ratings, and the like. The crucial 
question still remains: "How might these variables be related to the occur- 
rence of accidents in underground metal and nonmetal mining?" 

To answer this question, several of these variables were analyzed in 
terms of their correlations with the frequency of accident data obtained from 
the 1978 HSAC accident file. Table 3 presents a summary of this analysis. It 
is important to note that these calculations were based upon data from all 
unit operations in combination, not for any one unit operation in particular. 
They are, therefore, to be considered very general. 

TABLE 3 . - Correlation between beam, penumbra, floor, and surround luminance, 



and number of accidents for all unit operations 


Beam 
luminance 


Penumbra 
luminance 


Floor 
luminance 


Surround 
luminance 


r = -.37 
accidents p < 0.04 


r = -.41 
p _< 0.02 


r = -.36 
p _< 0.05 


p = -.32 
p _< 0.07 



It can be seen from Table 3 that beam, penumbra, floor and surround 
luminance all appear to be significantly and inversely related to the fre- 
quency of accidents in underground metal and nonmetal mining. That is to say, 
the more luminance generally present at the working areas in the underground 
environment, the less the accident frequency. It is important to qualify this 
finding by information gained from observation of interviews with underground 
personnel. There is likely to be an "optimal level of luminance" such that 
increases in luminance are associated with decreases in accidents up to a 
point , at which point further increases in luminance might be associated with 
an increase in accident frequency, if the sources of increased luminance are 
not properly distributed. Presumably, and with the illumination results in 
mind, this may be due to glare problems. A case in point is the situation in 
trona mines, where miners often complain of too much light in some areas and 
not enough in others, and claim that this often hampers their performance. 



328 

To determine the relative contributions of these illumination variables 
to accident frequencies, a multiple regression analysis was performed with 
beam, penumbra, surround, and floor luminances as independent variables, and 
accident frequency as the criterion variable. The results of this analysis 
indicated that penumbra, beam, and floor luminances (in that order) were all 
significantly associated with accident frequency. According to the present 
data, beam and penumbra luminance account for 30% of the variance in accident 
frequency. 

A note of caution is in order. The accident frequency data and the 
luminance data used in the present regression analysis are from two distinct 
sources. Thus, statements of casual relationships among these data are not 
possible. However, the results of the present regression analysis highlight 
the importance of illumination as a potential key factor in underground metal 
and nonmetal mining accidents. 

CURRENT ILLUMINATION IN METAL AND NONMETAL MINING 

The results of our mine visits, interviews with experienced underground 
workers, and illumination laboratory analyses lead us to several distinct 
conclusions regarding the present lumination conditions in underground metal 
and nonmetal mines . 

Metal and nonmetal mines are characterized by great variability of illu- 
mination environment. There are significant differences in (1) the size of 
the opening, (2) the reflectance of the face, and (3) the luminance of the 
work site within any given mine. There are significant differences between 
mines in the width of the opening and the reflectance of the ore. In addi- 
tion, across the various mining methods, width of openings also may vary 
significantly. There are great differences across the entire industry in the 
equipment used and the unit operations performed. Luminaire types and number 
of luminaires vary both among mines and within a given mine. The area requir- 
ing lighting also varies greatly. For example, one day it may be necessary to 
illuminate the full extent of a large open stope for slushing, whereas, the 
next day only a small corner need be illuminated for feedleg drilling. 

Just as the area requiring illumination may vary, one notes that the 
amount of illumination required for each task also varies. The task analysis 
indicated that each unit operation has unique requirements for acuity, depth 
perception and accommodation. The task analysis data and observations during 
the mine visits also indicated that wherever a given unit operation was found, 
it had the same visual requirements, despite differences among mines or mining 
methods . 

It has already been pointed out that visual discrimination of any sort is 
best done over a certain range of adaptation luminance and contrast condi- 
tions. This optimum range is bounded on the lower end by conditions too dark 



329 

or contrasts too low for adequate performance, and on the upper end by exces- 
sive amounts of light and contrast that result in discomfort and disability 
glare. Optimum conditions should be provided in underground mining. Provi- 
sion of enough light is only a part of the problem. The manner in which the 
light is controlled (by proper placement, luminaire design, and shielding) and 
the quality of the light (spectral energy content, steadiness) are equally 
important, yet frequently neglected in current mining practice. Eventual 
recommendations for mine lighting must take full account of these consider- 
ations . 

Additionally, it is important to note that increased luminance for 
various unit operations may be achieved in several ways; these include: 
(1) increase the number of luminaires, (2) increase the lumen output of the 
present luminaires, or (3) rearrange the configurations of luminaires used in 
the various unit operations. Our data indicate that, in general, the amount 
of luminance may not be the most critical factor but the distribution of light 
at working sites may be more important. That is, it appears that luminance 
may need to be increased in certain parts of the working area and not in 
others. Thus, it is entirely possible that in many cases a simple rearrange- 
ment or redistribution of light sources in the working environment may be the 
most effective method to solve some of the illumination problems which have 
been noted with regard to the working environment . 

Although the minimum luminance requirements for the unit operations found 
in the metal and nonmetal industry are yet to be determined, it is unlikely 
that a single standard will prove appropriate. But, if not a single standard, 
how are the standards to be defined? The current research indicated that the 
factor most influencing the amount of luminance needed is the task or unit 
operation being performed. Many different unit operations take place at a 
given type of work site, and are each likely to have differing luminance 
needs. If those differences are small, a standard based on the type of work 
site or perhaps even a single standard would work. The answer to the above 
question will only be found with the determination of the minimal luminance 
requirements for each task of unit operation. 

DETERMINATION OF MINIMAL LUMINANCE REQUIREMENTS 

At this point, we have (1) identified the illumination characteristics of 
underground work locations, (2) determined the gonioref lectance of sampled 
surfaces in metal and nonmetal mines, (3) identified the underground work 
activities, and (4) identified the accident and employment distributions for 
underground mining. However, several more pieces of data are required to 
determine the minimal luminance levels required for safe mining. These data 
are obtained through several steps including, (1) identifying the critical 
visual tasks, (2) determining the task visibilities, and (3) integrating the 
findings with previous research and with the standards of the Illumination 
Engineering Society. 



330 

The results of the task analyses serves as a basis for selecting the 
specific visual tasks to be evaluated. The task analysis provided the 
following information about each unit operation: 

(1) Frequency of occurrence in each mining method. 

(2) Common errors and accidents associated with performance of the unit 
operation . 

(3) Inherent hazards associated with the unit operation. 

(4) Difficulty of performing the unit operation. 

(5) Visual tasks involved in the performance of the unit operation. 

Each job task involves several visual tasks. For example, the unit 
operation "slushing" involves such visual tasks as detecting frayed slusher 
cables and identifying rock bolts in the muck pile. It is neither feasible 
nor necessary to determine required luminances for all visual tasks of each 
and every unit operation. Rather, it is important to identify the visual 
tasks that are critical to the safe and efficient performance of the unit 
operation. Determination of the minimal luminance requirements of this subset 
of visual tasks will define the minimal luminance requirements of the asso- 
ciated unit operations. 

Visual tasks will be selected that are performed frequently, or are 
infrequently performed but are critical. Errors and accidents associated with 
the visual task will be judged in terms of the contribution illumination might 
play in them. Visual task difficulty will also be considered. The critical 
visual tasks will be selected on the basis of the following criteria: 

(1) Safety, i.e., the consequences of an error to the operator. 

(2) Productivity, i.e., the consequences of an error to the efficient 
performance of the entire unit operation. 

(3) Importance, i.e., the frequency of performance and time needed to 
perform the task. 

(4) Prevalence, i.e., how often the unit operation associated with the 
task is performed across the industry. 

Once the subset of critial visual tasks is defined, it will be possible 
to identify those tasks common to various subsets of unit operations. It is 
anticipated that some critical visual tasks may be unique to a single unit 
operation. 

Two things are necessary for adequate visibility of a task in the mining 
environment: (1) sufficient luminance and (2) adequate contrast between 



331 

objects and their background. Illumination, or illuminance as it is sometimes 
termed, is the intensity of light per unit area incident on a surface. How- 
ever, for the purposes of determining the visibility of a task, illuminance is 
not enough. Thus, task visibility is specified in terms of luminance which is 
the intensity of light per unit area reaching the eye. Luminance determines 
the adaptation level of the viewer. As adaptation level increases, when all 
other parameters are constant, visual performance improves. 

Illuminance interacts with the reflectances of the materials to determine 
the luminance perceived by the individual. For example, fixed illuminance of 
a coal face, where the reflectance is low, would be expected to produce lower 
luminances than the same illuminance of a salt face where the reflectance is 
higher. Because adaptation level is determined by luminance, adaptation 
level, and thus visual performance, would be higher in the salt mine than in 
the coal mine (if all other factors are the same). 

For an object to be visible, it must have, in addition to an adequate 
luminance level, sufficient light/dark contrast with its background. The 
illumination methods now used in many mines may severely degrade contrast 
because of glare and scattered light from particles in the air (aerosols, 
hydrosols), from deposits on the miner's eyeglasses, and from particles within 
the eyes . 

Glare or scattered light, whether created within the eye or outside the 
eye, adds a veiling luminance to the retinal image of the mining task. This 
veiling luminance washes out scene contrast just as turning on the room lights 
washes out a projected color slide. In many mine environments, the loss of 
contrast due to glare and scattering may constitute a greater problem than the 
absolute level of luminance itself. 

As an example, assume that in a given mining task the target object has a 
luminance of .058 cd/m 2 (.2 fL) , and the background has a luminance of .029 
cd/m 2 (.1 fL) , a light/dark contrast ratio of 2:1 (100% contrast). Assume 
also that a veiling luminance of .029 cd/m (.1 fL) is created by ambient 
light scattered from particles in the air and from deposits on the miner's 
glasses. This .029 cd/m 2 (.1 fL) is added to the .058 cd/m 2 (.2 fL) of the 
target object: .058 + .292 = .350 cd/m 2 (.2 + 1.0 = 1.2) and to the .029 
cd/m 2 (.1 fL) of the background: .029 + .292 = .321 cd/m 2 (.1 + 1.0 = 1.1), 
thus washing out the previous 2:1 contrast ratio to only 12:11 or 1.09:1 
(about 9% contrast). If, in addition to producing veiling luminance, the 
scattering particles also cut the transmission of target object luminance by 
half, the resulting contrast ratio will be further degraded to 11:10.5, or 
1.05:1 (about 5% contrast). This is close to the threshold limit for contrast 
visibility in the operational mining environment. 

In a task environment that produces a significant amount of glare and 
scattering of light, an increase in the absolute level of task luminance is 
often accompanied by a proportional increase in the amount of veiling lumi- 
nance, with no net gain in visibility. This is well illustrated by the effect 



332 

of using high beam headlights in fog: any gain in highway illumination is 
negated by an increase in veiling luminance which washes out the roadway 
scene . 

A careful analysis of each task environment is necessary to determine in 
what ways any increase in illumination may be negated by increased glare and 
scattering, and how the ratio of target luminance to veiling luminance can be 
increased to improve visual contrast . 

These two factors of luminance and contrast interact; at lower luminance 
levels more contrast is required to see a given object or task, and the illu- 
mination methods now used in many mines may severely degrade contrast because 
of glare and scattering of light from particles in the air (aerosols, hydro- 
sols), from deposits on the miner's eyeglasses, and from particles within the 
eyes . 

Finally, to make sound recommendations regarding minimal luminance ranges 
needed for safe and efficient job performance in underground metal and non- 
metal mines, it is essential that all relevant factors in the visibility of 
tasks be considered. This means integrating the data obtained in the current 
research with those data in the coal mine illumination study (Hitchcock, 1973) 
and with the standards of the Illuminating Engineers Society (Kaufman, 1981). 
From these integrated data will be drawn the recommendations for minimal 
luminance requirements. Such recommendations must also give full weight to 
factors known to limit task visibility, including: 

(1) Disability glare. 

(2) Scattering due to aerosols and hydrosols. 

(3) Transient adaptation effects ("temporary blindness"). 

(4) Losses due to protective eyewear. 

(5) Vision requirements of the mine population ("the aged eye"). 



333 

REFERENCES 

Crooks, W.H., Drake, K.L., Perry, T.J., Schwalra, N.D., Shaw, B.F., and Stone, 

B.R. "Analysis of Work Areas and Tasks to Establish Illumination Needs in 

Underground Metal and Nonmetal Mines." Bureau of Mines Contract J0387230, 
1980. 

Hitchcock, L.C. "Development of Minimum Luminance Requirements for Under- 
ground Coal Mining Tasks." Bureau of Mines Contract H0111960, 1973. 

Kaufman, J.E. (Ed.) IES Lighting Handbook; Application Volume and 
Reference Volume . New York: Illuminating Engineers Society, 1981 . 

Trotter, D. Mine Lighting. Canadian Mining Journal, July 1977, pp. 24-31. 



334 



President 
Members : 



APPENDIX A 
Members of TC4.10 International Mine Lighting Committee 
A. Peretiakowicz (Poland) 



Australia 



Bulgaria 



Canada 



Czechoslovakia 



Jim Munro 

NSW Department of Mines 
132 Londonderry Road 
Londonderry 2753 

Ing. G. Gantchev 

c/o Comite National Bulgare de l'Eclairage 

Rakovskistr 108 

P.O.B. 612, Sofia 

Prof. D. Trotter 

Department of Mining & Metallurgical Engineering 

McGill University 

3480 University Street 

Montreal, Quebec H3A 2A7 

Ing. M. Lazar 

c/o Czechoslovak National Committee of the CIE 

Jankovcova 15 

170 04 Praha 7 



Denmark 



Mr. Hans Hilsoe 
c/o Lysteknisk Selskab 
Herlev Hovedgade, 188 
DK-2730 Herlev 



Finland 



France 



Germany FR 



R. Heikkinen 
Outokumpu Oy 
Outokumpu Mine 
SF-83500 Outokumpu 

Gabriel Portal 
Chambonnoyes de France 
9 Av. Percren BP 396-08 
75360 Paris 

Dr. -Ing. Bruno Weis 
Adolf Schuch KG 
Mainzer Strasse 172 
6520 Worms 



335 

Great Britain G. Heatherington 

Victor Products Limited 

PO Box 10 

Wall send, Northumberland 

Hungary Pal Esztergar 

Ing. Dipl. 
VEGYTERV 
Budapest, Hungaria krt . 178.H-1146 

Italy Prof. G. Gecchele 

Centro per la Sicurezza del Lavoro e di Scavo 
Instituto di Arte Mineraria Politecnico di Torino 
Corso Duca degli Abruzzi, 24 
10129 Torino 

Japan Shinzo Kato 

Nat'l Research Inst, for Pollution & Resources 
Agency of Industrial Science & Technology 
Onogawa, Yatabe, Ibaraki 305 

Netherlands Dr. F. Burghout 

Nederlandse Stichting voor Verlichtingskunde 
Utrechtseweg 310, Arnhem 

Poland A Peretiatkowicz 

40-855 Katowice 
ul . Gliwicka 111 

Rumania Eugenia Sufrim 

c/o Comite National Roumain de l'Eclairage 

Calea Victoriei 118 

Bucuresti 

South Africa Mr. R. Hemp 

Rand Mines Ltd. 
PO Box 62370 
2107 Marshalltown 

Spain S. Perez Cutillas 

Comite Espanol de Iluminacion 
Serrano 121 
Madrid 6 

USA Cecil E. Lester 

Mine Safety and Health Administration 
PO Box 1166, Building F 
Beckley, WV 25801 



336 



USSR V. I. Serov 

c/o USSR National Committee of the CIE 

SOVMEK 

Gorky Street 11 

Moscow 



337 



APPENDIX B 
MEMBERS OF TC4.10 AMERICAN MINE LIGHTING COMMITTEE MEMBERS 



Cecil E. Lester, Chairman 
Mine Safety & Health Admin. 
PO Box 1166, Building F 
Beckley, West Virginia 25801 



Glenn Beckett 

United Mine Workers of America 
5411 Starling Drive 
Charleston, WV 25306 

George Bockosh 
U. S. Bureau of Mines 
P.O. Box 18070 
Pittsburgh, PA 15236 



William H. Lewis 
U. S. Bureau of Mines 
P.O. Box 18070 
Pittsburgh, PA 15236 

Charles Maus 

Mine Safety Appliances Company 

Evans City, PA 16033 



Jerry Burgess 
Mcjunkin Corporation 
P.O. Box 513 
Charleston, WV 25322 



James A. Muto 

Research and Development Engineer 

FMC Corporation 

P.O. Box 992 

Fairmont , WV 26554 



Kurt Catob 

Ocenco, Inc. 

P.O. Box 269 

101 Industrial Park 

Blairsville, PA 15717 



Jim Oakes 

Mine Safety & Health Admin. 
P.O. Box 1166, Building F 
Beckley, WV 25801 



Dewey Dixon 

Lee-Norse Corpooration 
401 Rag land Road 
Beckley, WV 25801 

Mike Formica 

National Mine Service Co 

U.S. 22-30 

Oakdale, PA 15071 



Nathan E. Passman 
Flexible Lighting, Inc. 
892 West Street 
Woodstock, IL 60098 

Randolph E. Slone 
Westmoreland Coal Company 
Drawer A & B 
Big Stone Gap, VA 24219 



H. W. Hofstetter 

LaArboldea Condominum 

Apt. 1203 

Guaynabo, Puerto Rico 00657 

Kenneth P. Klouse 

Approval & Certification Center 

RR 1, Box 201B 

Industrial Park Boulevard 

Triadelphia, WV 26059 



Kenneth L. Whitehead 
Supervising Engineer 
Bituminous Coal Research, Inc 
350 Hochberg Rd., PO Box 278 
Monroeville, PA 15146 



<rU.S GOVERNMENT PRINTING OFFICE: 1982 - 505 - 002/48 



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